The Tribeca Film Festival kicks off its seventh year tonight at the Zeigfeld Theater with the big sparkly premiere of Baby Mama. The movie is about a single and successful businesswoman (Tina Fey) who hires a working-class woman (Amy Poehler) to be her surrogate. Can you believe we’ve gotten this far along in life without a wacky surrogate movie? Ms. Fey and Ms. Poehler will be hitting the red carpet on 54th street, along with their director Michael McCullers, and cast members Dax Shepherd, Sigourney Weaver, Steve Martin, and producer Lorne Michaels (natch). We’re thinking this is just about the only movie around that can boast an invited guest list that includes Caroline Kennedy Schlossberg, Fred Durst, and Padma Lakshmi.