It's true that there are 13 companies that pitched yesterday but haven't launched. And one that didn't pitch at all. Attendees at Demo Day aren't asked to sign NDAs. There's just a gentlemen's agreement (sexist term isn't it?) not to write, tweet, blog, etc. about the companies that haven't launched yet.

With regard to the points Harj and others make in this thread about TechCrunch, I have no idea if they have a policy of turning up their nose at companies that have already been covered elsewhere. I certainly would never agree to YC's off-the-record request for that reason. I observe it because I think the YC companies deserve a chance to control how they make their first big public splash.