360 Died Again, Need Advice on PS3

Second red ring and honestly, apart from Reach not really that interested in much the 360 has to offer.  I'm not too up to speed on the PS3 lineup so my question is are there any non-MW2 shooters that have large and active communities?  I know SOCOM is coming out later this year so that'll probably be hot, but what's everyone playing right now?  Thanks in advance.

Uncharted 2 has a solid fanbase.  It's not as popular as it used to be but there's still around 50,000 people on every day (mind you, not simultaneously).  It also has quite a few co-op modes which are really fun as well.

Bad Company 2 has a very active community, but if you're into shooters chances are you've played that on the 360.  
 
Apparently MAG is still going strong. I never got into it but I have a couple friends who swear by it. Uncharted 2 is probably my personal favorite on the console though. You never have a problem finding a game, and Naughty Dog are constantly doing updates and tweaks to expand the multiplayer and make it as awesome as possible. For example, they are running "The Lab" right now which is a series of different playlists (usually one every weekend or every other weekend) and then the most popular mode(s) will become regular playlist options. I forget this weekends, but last time it was 2v2 deathmatch, and it was really fun. Uncharted 2 has a lot to offer if you want a game to sink your teeth into.

Thanks for the advice, I totally forgot about Uncharted but that's awesome that its still alive.  Anyone play or know about Killzone's community?

I think Killzone is still alive, but barely. It seemed to be a very hit or miss title, a love it or hate it kind of deal. I do imagine some of the hardcore Killzone fans are still kicking around though. 

Killzone 2 is still alive, but the community is so fragmented that it really depends on how you like to play the game.  It's one of those games that allows players to make any kind of lobby they want, so everybody makes their own idea of a great match-type and they end up creating smaller player pools.  You'll be able to find a game regardless, but you'll have more or less options depending on how you like your multiplayer to be.
 
Resistance 2 is still alive, too, if you're into that sort of thing.

Socom, Uncharted, Killzone 2 (3 soon.) Probably MAG but I wouldn't get that if I was you. BF obviously. Loads of shit still going.

Yeah Killzone 2 still has quite a few games going on, depending on the time of day you play.  Most games nowadays are 32 player Warzone matches without friendly fire, so things can definitely get a little hectic.  Still, it's one of my favorite multiplayer games and I'll hop on from time to time.

MAG has a pretty decent community behind it 
 
BBC2 as others have said