mw2
I seriously wouldn't even bother with MW2. The whole point of a game is to be somewhat fun, MW2 is just frustrating and aggravating beyond belief. It's also filled with hackers, glitches, microphone spamming twats, noobs with ridiculous tactics, unbalanced weapons and no customer support whatsoever.
However, if you're interested in the latest Call of Duty games I'd suggest Modern Warfare 1 and possibly World at War if you haven't played the first three and UO. Modern Warfare 1 is much more balanced, much better map design and is overall superior (besides its financial success) to its sequel.
If you're interested in FPSs you might want to try BFBC2 which is ridiculously fun, it has a fully dynamic environment, with some acceptable visuals and awesome tactical gameplay.
GTA4
Whilst it isn't as good as some of its predecessors (San Andreas for example) since it's possibly the only one available on PS3 (?), it's probably worth the buy. It's still a pretty fun game.
If you're into these kinds of free-roam gangster games you might want to try Saints Row and its sequel, The Godfather which has a wonderfully executed 1930s setting, and, when it's released (and if it's released for PS3), APB (All Points Bulletin) which is basically a mix of GTA and MMO with
awesome character customization. little big planet
This is a must get. Great game. It has a very nice concept, is very interactive - very good value for money.
and someothers
One of the good things about PS3 is the exclusive games. The two big PS3 exclusive video games currently on the shelves are probably MAG and Heavy Rain. MAG is basically a tactical shooter with 256 player online - which sounds incredibly fun - and Heavy Rain (haven't looked much into it yet) looks like an adventure where your choices can alter the outcome of the game a lot and different character have different options therefore resulting in different endings.
You might also want to check out Dantes Inferno, which is a PS3 exclusive but wasn't rated very well because it's pretty much a carbon copy of God of War with worse gameplay. So Dantes Inferno or God of War might be good choices for beat-em-ups.
The problem is I don't really know what kind of games you're looking for. Give me a sort of outline of genres you're interested in and I might be able to help out a bit more.
