Game, set, match.

The Observer took in a few rounds of racquet sports last week at the stunning Tennis Club Grand Central, a single court hidden within the train station. The event mixed tennis pros with tech types, including First Round Capital's Charlie O'Donnell and Social Media Week's Toby Daniels.

It was all part of Get Served, a tech-meets-tennis event put on by hostess with the most-est Emily Gannett and her IRL productions. We didn't quite make it to the finals, a doubles match involving AdWeek's Dylan Byers. Sadly Mr. Byers and his partner lost to a pair of stunning sexy-tagenarians, who proved consistency, not power, is the real killer on the court. Better luck next time, Mr. Byers.

After all the balls were played, The Observer joined former Wired writer Eliot Van Buskirk, who now runs the music app blog Evolver.fm, to have our swings recorded and analyzed via video. Mr. Buskirk, a former tennis coach at Harvard, had the better forehand, but we proved once again to be the master of the backhand (compliment).

From there it was off to the bar, where we sipped some 18-year-old cherry oak-aged Macallan single malt and discussed the finer points of startup life with Mr. Red Tie himself Gary Sharma, ER Accelerator's Murat Aktihanoglu.

Ms.  Gannett grabbed us and steered us towards the photo booth. "Get your picture taken with Roger Federer." And there he was, that rough smile, dimpled chin, astonishingly large head. He seemed smaller in real life ... and had a bit of a gut.

"Pretty good right? I found him on Craiglist," Ms. Gannett explained of her photo Federer. Personally The Observer would have used Zaarly, but same difference. As we headed out for the night, Foursquare co-founder Naveen Selvadurai was checking in for a photo with Faux Federer. Priceless.

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The company released this amazing infographic to share some of the highlights. 

There were 381,576,305 check-ins all told, with the biggest single event being the 30,525 checkins at the Rally To Restore Sanity in D.C.

Perhaps most impressive was the range of locations that earned top honors. Japan, Australia and Thailand all had some of the top locations for Foursquare check-ins. 

As we noted earlier this morning, Foursquare's value is now north of $250 million and it plans to double its staff in the coming year. 

bpopper [at] observer.com | @benpopper

Bloomberg reports:

Foursquare, which Selvadurai said will probably have 10 million users by June, faces increasing competition from location-based services now offered by social media sites Facebook Inc. and Twitter Inc. Foursquare expects to profit by forming more partnership with local businesses and offering more recommendations, including places to have dinner or grab a drink after a music concert or show.

Selvadurai also said Foursquare is set to double its employee headcount to 120 by year's end. That would match its doubling in value, as the company was worth a reported $120 million in June of last year.

The company will probably raise another round of funding later this year, Selvadurai told Bloomberg, but is in no hurry to earn that "Profitablity" badge according to co-founder Dennis Crowley. 

Update: A Foursquare spokesperson disputes the Bloomberg item. Here is the note she sent us:

I wanted to give you a heads up that the stories circulating about our valuation and fundraising plans aren't true. Naveen was asked about our valuation in an interview after a panel this weekend, but he didn't make any comments about this, or suggest that we're currently thinking about another round of fundraising. Let me know if you have any questions.

We do have questions, and will update when we hear more.

mtaylor [at] observer.com | @mbrookstaylor

"I'm incredibly excited to announce something I've been dreaming about for so long: Foursquare is going to have its first ever developers meetup," Mr. Selvadurai wrote to the 1,841 members of Foursquare's developer listserve.

The event is happening in New York City on Feb. 5, details to be announced.

Chris Thompson of the Ohio-based blog About Foursquare floated a few ideas for Foursquare-based apps:

Here are a few things I'd love to see:

A way to browse nearby specials in real time using the API's new specials endpoint.

A nice-looking map I can share on Facebook, Twitter or my website that shows the places I unlocked each badge.

A tool that can look at my history and my friends' histories and suggest places to meet up for dinner or drinks that we all like.

Marshall Kirkpatrick from ReadWriteWeb suggests another:

I'm cheering for someone to build a Foursquare mashup with Google News and Wikipedia, so I can be told automatically when the places I go have been mentioned in the news or have history posted on Wikipedia.

The time and place is not set yet but Mr. Selvadurai wanted to announce the date as soon as possible so developers can make plans to travel to the city.

ajeffries [at] observer.com | @adrjeffries

To get in, revelers just have to show up, check in on Foursquare via their mobile phones, and voila, the building’s door will open for them.

“We’ve been using the system to get in for over a month now,” says Hall. “People think we’re psychic, because they see us showing up to the apartment and getting buzzed in the second we arrive.”

Sparling, 30, and Hall, 28, grew up together in Pittsburgh. “Nick and I have always just taken our crazy ideas and tried to make them real,” says Sparling. “We have a lot of plans for ways to automate the house, like a couch analytics system that tells you which person has been sitting on which cushion and for how long, or a fridge cam that tracks who eats what.”

Check Out The Brothers' Incredible Apartment >>

Sparling leads the Design Technology department at the Wall Street Journal, where his brother is a frequent consultant. The pair have turned their apartment into a hi-tech home studio, filled with equipment for photography, development and design.

“The way this Door invention came about is, we have all these great gadgets and we wanted our friends to be able to use them,” says Hall. “So we brought in some extra desks and turned this place into a sort of co-working space.” They named the spot Apartm.net, which is also their website.

Instead of just making everyone a spare set of keys, the brothers decided to experiment with Foursquare’s new API. “We’re friends with Naveen Selvandurai, Foursquare’s co-founder, so he gave us an early look at the new API and asked us to build something cool.” Over the course of one weekend in November, the “Door” project was born.

"The developer API allows people to have an incredible amount of access to data that's generated by Foursquare. So one can build applications with great breadth: from games that are built on top to visualizations of checkin history to maps of trending places in your city," says Selvandurai. "We particularly like this hack because it has an interaction with the physical world – and part of the goal of Foursquare is to get you out from behind your computer at home."

The brothers have made a video each year to promote their New Year’s Eve bash, but this year things have become a little more complicated. “The video has gone viral on the web, so yeah, we’ve sort of invited millions of folks to come to our party,” says Hall with a laugh.

“That’s ok, we love the internet,” says Sparling. “We live there.”

The boys sat down last night for a late-night planning session. On the agenda, designing a Do-It-Yourself kit that would allow anyone to recreate their Door project on their own. “The software part, with Foursquare, is easy,” says Sparling. “But creating a door attachment that works universally is going to require some thinking.” They are considering creating a Kickstarter project to fund the development.

Extra planning will also be necessary to protect the boys' incredible assortment of geeky items if the party turns into a mega-rager. A shrine in the living room features every single console ever made by Nintendo, including the original Gameboy with both the camera and printer extensions.

Their prize possession is the coffee table. It's a G4 model Xserve, the server that powers their personal website, among others. “We try not to spill too much beer on it,” says Hall.

Check Out The Brothers' Incredible Apartm.net and See Photos From Their Last New Year's Eve Blowout >>

The young millionaire favors the East Village, where both the Foursquare offices and his old apartment are located, but really, who can resist the magnetic pull of Silicon Alley's favorite cast-iron hood? The airy loft at 428 Broome Street boasts 1,200 square feet, but only a single bedroom. With its 13-foot ceilings and exposed brick, the apartment was fodder for some New York Times house porn when it was last on the market for $1.3 million in 2006.

This time around it was listed by Corcoran's Dorothy Zeidman for $1.425 million, and sold for exactly that. Of course, Mr. Selvadurai's can well afford it, given that Foursquare is now valued at $80 million.

The seller is John Wotowicz, who bought the place with his wife at the time, Virginia Lebermann, in 2008. Ms. Zeidman declined to comment.

lkusisto@observer.com

Unfortunately, it's not speeding up either. It took a year for the company to reach one million users; three months to hit 2 million and a month and a half to hit 3 million.

Since then, however, it has added 1 million every 1.5 months, so user growth seems to have leveled off.

When Facebook debuted its Places platform, many in the tech press, The Observer included, speculated about what it might mean for Foursquare.

But the last quarter of 2010 has been great for Foursquare. It locked down major partnerships with big brands like Gap and Radioshack, added an office in Cali and brought on new hires in NYC.

Founder Dennis Crowley just tweeted that his company is working on a hot new Foursquare app. Now they just have to worry about alienating those core users...

UPDATE: Foursquare's Erin Gleason writes to say, "Although we're over 5 million in terms of user IDs, we haven't quite hit 5 million users yet. We should hit 5 million sometime next week." Devils in the details.

bpopper [at] observer.com | @benpopper

Crowley and Google parted ways in 2007, a decision he explained simply. 

It's no real secret that Google wasn't supporting dodgeball the way we expected. The whole experience was incredibly frustrating for us - especially as we couldn't convince them that dodgeball was worth engineering resources, leaving us to watch as other startups got to innovate in the mobile + social space. And while it was a tough decision (and really disappointing) to walk away from dodgeball, I'm actually looking forward to getting to work on other projects again.

In January 2009 Google shut down Dodgeball. In March of that same year, Crowley and co-founder Naveen Selvadurai launched Foursquare.

Today Crowley tweeted that his new startup, Foursquare, is adding 25,000 users every day.

Foursquare has been having technical problems recently; its website went down several times in the past week because too many users were checking in.

But if the company can manage its growth, things are looking very promising.

With mobile and Android exlpoding, Google probably wishes it had shown Crowley a little more love when it had the chance.

This kind of outage is common on Twitter, but the micro-messaging service has never been out for this long of a stretch.

Mark Zuckerberg is notoriously vigilant about preventing these kinds of breakdowns, having seen the disastrous effect that outages had on Friendster.

Still, even Facebook goes dark occasionally. This incident is emabrassing for Foursquare, but won't damage them permanently unless it becomes a pattern. Hell, if the service is addictive enough, maybe it won't hurt them. The Twitter fail whale is a pretty common sight, and that hasn't slowed the company's growth.