The only two contenders right now are MGS4 and GTA4.
LBP doesn't stand a chance
Fallout 3 doesn't stand a chance
Gears 2 cannot win because Gears 1 won just two years ago
All five will be nominated, but the winner depends on how much reviewers succumb to the hype.
A lot: GTA4
Not very much: MGS4
I'm going to say the nominees will be :
(B) = big chance
(S) = small chance
(N) = no chance
MGS4 (B)
GTA4 (B)
Gears 2 (N)
Resistance 2 (S)
LBP (S)
Fallout 3 (S)
Brawl (N)
Dead Space (N)
Sorry if that appears Sony biased, but for the reasons I've mentioned or just because they aren't good enough, several of those games lack the capacity to win.
And two of the following:
Paradise (N)
No More Heroes (N)
Civ Rev (N)
Sins of a Solar Empire (N)
Fable II (N)
(Former) Lead Moderator and (Eternal) VGC Detective 
