[kapitalx]

This list (allthingsd list) isn't complete. I'm not sure if there is a reason why some are missing, so I won't spill any names.

[jkincaid]

The other companies were "off the record". This is journalist lingo for stuff you can't write about. It's an agreement between YC and the press in attendance that they won't write about companies that don't want to be 'outed' as being part of YC (or haven't announced their existence at all).

Sure, someone could go and write about those companies anyway, but they wouldn't be invited back.

[rwar]

Theres another HN article with a more complete list, http://news.ycombinator.com/item?id=2356941