this talk with Erik Wolpaw on Thursday -- like, right now. You definitely won't be able to stroll in, and even if you do, you'll miss out on free croissant sandwiches.
It's open to the public. Go.
"The format for the evening will be a brief guided play-through of Portal 2 with Erik, followed by an interview and general discussion moderated by Game Center Interim Director Frank Lantz. The audience is encouraged to join the discussion. Please bring questions about Portal, game writing, criticism, narrative and the overall subject of games in general."
And the NYU croissant sandwich things are pretty awesome. Get there early if you expect any otherwise I'm going to eat them all.