Trust me, you won't see anything more than banners shrouded in black cloth, and if you're able to sneak into the exhibits hall during the setup (I managed it one year), an Apple booth surrounded by curtains with one entrance guarded by a big burly guy who exudes "don't mess with me." Apple security won't even let you get near the entrance to the ballroom.
You'd have to be very stealthy (and presumably willing to risk arrest) to get a look at anything before Steve says "alakazam!"