Here's a list of the fine companies that are supporting this event:
Google - They're hosting the event. 'nuff said. Kudos to Chris and Leslie for being the champions there.
Canonical - aka the Ubuntu company. They're supplying CD's to hand out for the install fest.
No Starch Press - They're giving away hot-off-the-press copies of Ubuntu Linux for Non-geeks
O'Reilly - the standard bearer for geek tech books. They have generously decided to donate copies of Ubuntu Hacks.