Nintendo has already stated Wii2 will be there in playable form havent they?
At least this E3 has two hardware launches, NGP and Wii2, even if they are second tier imo. First E3 in a while to see new hardware (3DS last year).
I agree E3 feels a little slow to me this year too though. Still hugely anticipating it though.
Software wise, well, some big Wii 2 titles (Mario, Zelda) hopefully. Zelda in 360+ quality graphics can get even a Nintendo hater like me excited. Of course the first real look at NGP. For MS, Halo Remake (at least I think so) Gears 3, Forza 4, Alan Wake 1.5, Codename Kingdoms...I dont follow Sony as much, and they seem to reveal things much earlier, so not sure what they'll have besides whats known like Uncharted and Resistance and Last Guardian...and as always there may be a big megaton surprise announcement or two (perhaps some shocking exclusivity announcement)...shoot I'd even hope for Doom 4 to show up though that may be only for Quake con. Plus MGS Rising, MW3, etc etc etc