I'll repeat it again, for added emphasis, and to use the FULL NAME.
Hideo Kojima's Metal Gear Solid (Tactical Espionage Action) 4: Guns of the Patriots, a Hideo Kojima game, directed and produced by Hideo Kojima, makeup by Ryan Payton :D
And hell, I'll add a fourth for each console. And a fifth, since Gamespot nominates 5. I don't know WHAT IGN does, and Gamespot seems a lot more organised with their GoTY awards.
PS3: Metal Gear Solid 4: Guns of the Patriots, Grand Theft Auto 4, Little Big Planet (it's three words now!), Resistance 2, BioShock (Valkyria hasn't sold enough, it will probably win 'best game nobody played')
360: Fallout 3, Left 4 Dead, Gears of War 2, Grand Theft Auto 4, Fable II
Wii: Mario Kart Wii, Super Smash Brothers Brawl, Animal Crossing, de Blob, um... Guitar Hero World Tour?
PC: Spore (goddamn it), Fallout 3, Call of Duty: World at War, Crysis Warhead, Sins of a Solar Empire? Don't really follow PC gaming...
PSP: Crisis Core Final Fantasy VII, God of War: Chains of Olympus, Patapon, N+, WipEout Pulse
DS: The World Ends With You, Final Fantasy IV, Professor Layton and the Curious Village, Castlevania: Order of Ecclesia, Ninja Gaiden Dragon Sword.
And I'll bold the game most likely to win (all my opinion of course).
Top ten contenders:
Metal Gear Solid 4: Guns of the Patriots
Grand Theft Auto IV
Gears of War 2
Fallout 3
LittleBigPlanet
Super Smash Brothers Brawl
Resistance 2
God of War: Chains of Olympus
The World Ends With You
Left 4 Dead