Yep, you nailed what I meant but didn't spend enough time writing.  I just get this feeling that, given the number of companies involved, the patent situation is a known quantity for MPEG-LA, whereas the situation around Theora hasn't been as well researched.  Unless someone with a massive amount of lawyers starts the ball rolling, I really don't see hardware people building accelerators into chipsets for Theora like they have done for h.264.