Okay, while these have already been mentioned I feel they deserve another mention, for outstanding performance in the field of exellence.
Uncharted

rake's fortune, this game doesn't do anything all that new, but it combines so many great gameplay elements so well. It Has a nice story with genuinely lovable characters, a great script and some fantastic acting. It might not reinvent the wheel, but it does what it does damn well.
Little Big Planet, this game should be on every PS3 owner's shelf, the ammount of things you can create is mind-boggling, you really are only limited by your imagination.
Yes the platforming itself is a little clunky at times, but the sheer scope of the level creator and the over-whelming charm of the design more than make up for it.
Killzone 2, this is a fairly standard FPS, it does most things strictly by the book, but it has a level of polish rarely seen. Not just in the graphics but the design, the set pieces and overall production. The gameplay has a lovely sense of weight to it, your character actually feels like he moves with a bit of mass.
It doesn't bring many new ideas to the FPS table, but it's an immersive, well designed shooter.