I can't wait to see what Sony's got planned. GOW3 is a given, as is the other known games and services(LBP, KZ2, R2, HOME, Socom, etc.)
What I'm most interested in is the unknown stuff. Sony's PR has been talking about the 3rd party exclusives issue for a little bit of time now, so they had to have seen this coming. Since they found out about FF13 from Square-Enix(undoubtedly behind closed doors weeks ago), I'm guessing they've been planning something big. I'm looking at Team-ICO, maybe Heavy Rain, and some other announcement.
Nintendo, like me, doesn't seem to much care about the 'winner' of E3 because they don't have to. No doubt, they'll introduce some cool-ass shit, probably Kid Icarus, new Zelda(early screens), and/or a new Mario proper game(farther off, but it doesn't hurt to announce the inevitable.) They'll show off the Wii cheerleader game, the Yoga one, as well. They'll also surprise with a new peripheral.
The winners-losers thing is blah for me. So long as Nintendo and Sony show off rockin' stuff, we all win.