Inside, the flashbulbs were blinding, accompanied by desperate shouts every time a Kelly Osborne, or a Kim Raver from Lipstick Jungle, or a J. Lo, or a freshly shorn and dyed and pixie-ish Victoria Beckham arrived.

"I'm really a plus one," said bewildered painter John Currin, taking in the scene with wife Rachel Feinstein, an artist and friend of Mr. Jacobs'. "People are better looking," he added, appraising the difference between art and fashion parties. "There's a lot more money, I think, and better-looking women."

Speaking of: "[Marc] buys art!" he continued. "He owns Rachel's work, he owns my work. I guess Rachel's more involved with his fashion side..." Ms. Feinstein was gone. He looked around for her, desperately.

Kim Gordon of Sonic Youth wore a short blue dress and black ankle-boots. Last season, she'd staged a surprise performance at Mr. Jacobs's show. "It was fun," she said. "I think Marc called up and asked about 10 days before the show." More than 15 years ago, Mr. Jacobs had appeared in the band's "Sugar Cane" music video with Chloe Sevigny, preparing his infamous "grunge" collection. Mr. Jacobs has long hair in the video and is wearing a flannel shirt. (How times have changed).

"I mean, the whole grunge thing was a joke, that was a made up term by the secretary that worked at Sub Pop [Nirvana's record company], the New York Times called her up, and she just made up all these fake trends, and the rest is history," said Ms. Gordon matter-of-factly, denying she'd ever been into grunge herself.

Winona Ryder (incidentally, star of grunge rom-com Reality Bites) arrived in all-black and pink patent-leather pumps. The paparazzi closed in on her.

At 9:10 a voice starting ordering people to take their seats. A desperate mob rushed over the elevated runway to escape gridlock in the aisles, while an impromptu mosh pit formed at the entrance as guests struggled to navigate the paparazzi bottleneck.

At 9:15, after several more entreaties over the P.A., the show started. A clutch of invitees who hadn't reached their seats was forced to stand at the head of the runway, beside the camera gallery. Jay-Z arrived at 9:19, in white T-shirt and sideways red Yankees hat. He was escorted to the front of this mob, where he took in the show standing, squished between agitated, black-clad hipsters, looking uncomfortable. (Stylist Rachel Zoe, meanwhile, who had been shut out last season for her late arrival, was happily ensconced front row many minutes before the show started).

There was no surprise concert, and no alcohol, like last season, but the clothes were shockingly good, even to the untrained eye: vibrantly colored, textured, African and Victorian-inspired, with turbans alternating with prim, flat hats; plaid shirts tucked into shiny, apron-ish wrap skirts, bags with a lot of gold hardware, and librarian glasses lending the whole thing a dose of the designer's trademark nerdiness. The whole thing was set to blaring Gershwin. There had been nothing like it so far this week. The crowd was exhilarated. This was a fashion show!

"I loved him from the very, very beginning, early on," gushed model Stephanie Seymour afterwards, in plunging dress, looking as fresh and dewy as a 25-year old. "We all used to do his show, we begged to do it, for free! We just all wanted to do it. We all adored him. He's a sweetheart and everybody always..." she trailed off, thoughtfully.

"He's really calm [backstage,]" she continued. "To me. Maybe he's trying to act calm but he always seemed very, very calm to me... And he's very creative, and finds inspiration everywhere, and is just sort of limitless, he doesn't allow limits to impose his... you know, vision."

She had walked the runway for Mr. Jacobs as recently as last season, she said, for his Louis Vuitton collection in Paris

"The nurse show, with Richard Prince," she said.

"You opened that show up," clarified her husband, Interview owner Peter Brant, seeming to revel in his good fortune.

(Meanwhile: "She looks fuckable," a man in army fatigues, one of the Armory's employees, was overheard saying).

The crowd moved downtown to Robert DeNiro's new Greenwich Hotel, causing a traffic jam of taxis and town cars in TriBeCa. The scene outside was madness: models and glamorous photographer Ellen von Unwerth waiting in a stationary VIP line, being shouted at by security guards.

Inside, Mr. Jacobs and his business partner Robert Duffy manned two long tables in a courtyard, hosting a private dinner for about 50 people-Sofia Coppola was at the head of one table, Ms. Zoe at the head of the other. Mr. Jacobs noshed on salad in a white button-down shirt and black kilt, seated beside boyfriend Lorenzo Martone. The courtyard began to fill with party attendees, spilling out of Ago restaurant and the hotel's lobby area, both of which had been commandeered for the event. Apparently, the crowd was becoming a bit much for the private dinner guests, and so access to the courtyard was restricted. This caused an angry pile-up at the glass door. "I'm with Kanye's party!" cried one attendee, in sideways baseball hat and white cardigan. Mr. West was nowhere to be seen.

A svelte Ms. Osborne was in the bathroom, lending her hairspray to goth-looking Marc Jacobs shopgirls. She wore a long, gauzy gown by the designer. "My boyfriend's going to be like, "What were you doing in there!" she remarked, to the shopgirls, and then sighed. "Male models."  She told them she'd been sent a bunch of Mr. Jacob's dresses in U.S. size 8, "which in the U.K. is like a size 16. I couldn't wear any of them."

Back at the entrance to the courtyard, the tension was rising. A 300-pound security guard put his head in his hands and looked about to cry. Sweaty-shouldered hipsters spilled each others' drinks and pushed desperately towards the door and the elusive Mr. Jacobs beyond it, perhaps figuring that with teamwork they could overpower the substantial musculature blocking their way.

Meanwhile, several feet away but undetected by the angry mob, a guy in a white t-shirt and sunglasses exchanged words with the DJ and then turned around and started rapping, sans microphone. The song was "Swagger Like Us," a recently-leaked collaboration between T.I., Kanye West, Lil Wayne, and Jay-Z.  The man rapping was-yes, it was-Jay-Z.

And then, suddenly, out of nowhere, next to him: Mr. West, in plaid gray suit and black-framed glasses. They sang together, bouncing up and down, gesticulating. Mr. West gave a cartoonishly exaggerated thumbs up when asked about Mr. Jacobs' show.  It took the crowd a minute to realize what was going on, but when they did, a security guard in suit and earpiece was ready, pushing them back, trying to maintain a modicum of space for the rappers. The guests raised their camera-phones in the air and descended like vultures.

Speaking of! Will the fashion industry's recent efforts to police the size of its models result in meatier mannequins this Fashion Week?

"I was hoping that it would be curvier models on the runway," said Mary Alice Stephenson, celebrity stylist and host of fashion's greatest reality show to date, America's Most Smartest Model. "I just did, this morning, a piece for CNN, everyone still says skinny models, skinny models, but I've noticed a big change. A lot of the samples that I'm working with are cut bigger, and a lot of the actresses I work with can fit into them, so that's good. But I still hope that—I'm hoping—that the models on the runway will look like they've been eating. Will be fed properly, be a little bit more mature and curvy."

The Council of Fashion Designers of America (CFDA) will man sustenence-promoting booths in the tents at Bryant Park throughout Fashion Week in partnership with an eating disorders clinic.

But don't expect to see models who ate as much on their summer vacation as you did: "The bottom line is, if you're a runway model, you have to be thin," said Ms. Stephenson.