PS3 Owner here, so here goes nothing. My top whatever, in no particular order:
Modern Warfare 2
Uncharted 2
Batman AA
Demon's Souls
(final slot reserved for either Assassin's Creed 2/Dragon Age/Infamous, since I haven't played them yet)
Notable games:
Chronicles of Riddick Dark Athena: Reminded me of why I loved playing single player FPS's so much
Street Fighter IV: Great game brought down by balancing issues & antiquated online matchmaking. Hopefully this'll get fixed with SSFIV.
Killzone 2: Above average single player, fun multiplayer. Guerilla might have bit off more than it could chew with 32 player games, the online game was tweaked too much to keep up with, and the map packs split the community up. Killzone 3 should deliver, though.
Resident Evil 5: Game was too easy and too much like it's predecessor. Still fun, and I lost countless hours to grinding my weapon and whatnot.
Letdown of the Year:
Borderlands. Not my cup of tea. Boring single player with stupid enemy AI and somewhat janky on the PS3. Even when the online was functional, it just wasn't enjoyable.