Right now, multiplayer CoD on PS3 is an absolute shambles. Modders have overrun MW and MW2, to the point where it is nearly impossible to find a clean game. Players are finding themselves thrust into unplayable matches, where care packages rain from the sky, desert eagles shoot nukes and people move at super speed. Worse, players are finding their stats reset, their hard-won unlocks removed, their ranks zeroed out. And players can't quit from those games, because the in-game pause menu has been disabled.
The thing that gets me about this whole situation isn't the existence of the hacks and mods, but rather Infinity Ward's response (or lack thereof) to them. They've basically thrown up their hands and said "it's Sony's fault." While there is plenty of blame to pass around, I think the lion's share of it lies squarely on IWs shoulders. They failed to implement basic security protocols to ensure legit players are not affected by mods, and now they are seeing the results of that failure.
I guess the point I'm trying to make is, right now, if I owned a copy of MW2 on PS3 (which I don't; I own it on 360) I would be enraged, because right now the multiplayer portion of the game is borderline unplayable. As it is, all I can do is comisserate with my PS3 brethren.