Ogg Theora
Just an FYI, On2's the company that released the VP3 video codec under an irrevocable free license (including covering any patents On2 has, including for commercial use), specifically to provide a basis for the Ogg Theora video format. So they are definitely supporters of open source software.
I wonder if Google will open up VP6 (especially if it has any advantages over H.264.) Then it could be used for in-browser video. HTML5 video tag for newer browsers, and flash for older ones (since flash also supports VP6).