i expect to see a lot more of all the games shown so far.
pgr3 playable (or at least demo'd)
gr3 playable
EA's titles sports line up
EA's after launch games in some form (burnout, battlefield, fight night, def jam, etc)
pd0 playable, and this to be MS's focus
etc
i'm hoping MS will unviel quite a few titles "on the horizon". stuff like shadowrun, the darkness, secret titles. things that should look better then most (all?) the launch titles and be out around mid next year. gears of war fits in here as well. i expect new environments to be shown, vehicles, monsters. basically, its real unveiling.
then of course, i'd love to see halo 3 in some form. maybe even just an official announcement with the tiniest bit of info. i'm pretty doubtfull it will be out next year, but if it is, its certainly not to early to let the world know about it. an announcement wouldnt overshadow the launch titles, but would draw a lot of important attention.