Thanks, I did hear about this yesterday, but it's too late to register. They're allowing people who can figure out how to insert themselves into the database to register (the code for the site is open source and has hints on how to do it), so I'm about to clone the git repo and look around.
Startups and small companies like Twitter, GitHub and Heroku are going to be there. I think registration is already closed, but maybe you take down the list of companies and apply to a few specific ones you like directly. Yeah, I know how the job market is, but often there are many cool companies that are overlooked because they don't have the 'brand names' like Google or Microsoft.