It depends what you'll be using it for I guess, and which game series' you like. Anyone saying 'get PS3, better exclusives' really has no idea at all! If you're a fan of Resistance and Uncharted (there are more, I realise) then the PS3 is an obvious choice.
If, however, you like the Halo's (or maybe haven't played them yet?) and Gears of War's of this world, then the 360 would be the obvious choice. Personally, having owned both (sold the PS3 though), I'd say that if the PS3 exclusives don't really appeal to you, then go with the 360, with a view to getting a bit more storage space further down the line. With the way Microsoft are evolving Xbox Live, integrating Kinect (among other things) with the Dashboard and the astonishing Xbox Live Arcade, I'd say that'd be the way to go.
If you're unsure, I'd always recommend the 360...Blu-ray aside, the PS3 doesn't offer
that much. With a better online service, achievement system and all round community, I'd say that the 360 is a safe bet for anyone currently 'on-the-fence'

I'm not fanboying for Xbox btw, just offering an opinion...both have their strengths, and both are
very good systems...take from it what you will