9/20 PS3 games involve guns. Note, I am counting MGS4 and Warhawk here.

0/7 PSP Games.

I counted it once. About half of them if I'm not mistaken.

PS3: 12/20 (14/20 if you count Infamous and Marvel Ultimate Alliance 2 since the bad guys have guns)

10/47 Wii (11 if you count Blast Works and guns that go PEW PEW PEW)
3/6 X360

No idea dont wanna go count all my games but ill guess a very high percentage!

2/23 Xbox 360 games rely heavily on guns.

Bullet witch and Lost Planet

I tend to avoid games that use guns.

@ WarmachineX )

uhm, you are avoiding guns with _that_ nick??

16/25 PS3 games ( Disgaea 3 has guns :) )
2/5 Wii games (No more Heroes has enemies with guns... does it?)
3/7 PSP games
2/4 PSN games (FF always has guns in it...)

EDIT: 16 PS3 games because I forgot Ratchet and Clank...

Probably all of them, except the driving ones, even LBP introduced them!  I was thinking about this yesterday, was playing a GBA castlevania game, and started thinking that there is nowhere near enough whips in games - It's an excellent weapon that is under-used in games.  I don't think I've ever seen a FPS use a whip yet, maybe someone should make a FPW (first person whipper)