Assassin's Creed 2 and Modern Warfare 2. The first of each of these are among my absolute favourites for the PS3, though now I have a decent PC I'm not sure which platform to go for - that'll depend on reviews more than anything, I think.
I'm interested in TFU: USE, and may get it eventually to play the DLC, but AC2 and MW2 are top of my Autumn-time wish list.
For early 2010 - Napoleon: Total War, Mafia II
and Final Fantasy XIII
look very appealing!