There is already a 1 minute trailer of this game, and it looks amazing.  So yeah, I certainly expect to see more on it.  The biggest SURPRISE would be a Wii Chrono game, or Wii KH.  I don't see either of these happening though.  More realistically:  Some good Wii RPGs like a Golden Sun game, some new IP from SE, some from the ground up Nintendo RPG, and a LOT of 3rd party game anouncements for Wii, as the 3rd parties attempt to prove that they are supporting the most popular system.

GTAIV announced as exclusive to the Xbox 360...

their won't be any big suprises ,because for every possible thing there will be hundreds of people claiming "I knew it before"

I'm pretty sure I'm the only one who claimed Miyamoto would walk on water.

Hey, if something big happens at E3, great. If only fairly known or obvious things happen, there's a fairly impressive lineup coming out soon anyway, so it'll still be Christmas in July for gamers.

No GTA on Wii.

No GTA IV exclusive on 360.

PS3 Price drop to 400$ not happening. They don't announce price drops at E3 and it won't be a 200 dollar drop.

What I hope will happen: Killzone 2 footage looks somewhere near the previously shown stuff, but it's not likely.

Actual surprise announcement: UT 3 timed exclusive for PS3 (and PC) 

Anything announced in this thread instantly becomes not a suprise, therefore this thread fails.

Anyway, MGS4 announced as non exclusive.
Nintendo buys out microsoft and makes Bill Gates streak through Time Square.

Nintendo comes out with the Wii 2 at $400 pissing off many early buyers. (Their statement goes something like this "We didn't want to empasize on graphics but I had Bill Gates show me what Zelda would look on their hardware and................ well, graphics are better than gameplay!")

Microsoft shows off it's new pink color 360 with a Hello Kitty pack-in game. (when the system dies you get a yellow ring of flowers)

Sony drops the PS3. (that's it)

Well, we're on the same page it looks like...although I'll leave that UT 3 prediction to you, heh. 

Killzone 2 and fact it really looks and play like Halo 3 killer.

The biggest surprise will be how many exclusives ps3 is gonna lose now, imma gonna put up a counter for this one.