Don't own a PS3 myself, but I would definitely prefer the DLC be on both platforms. Sure, there's that urge to support the 'home team', but exclusives are a joke to me. It's almost always a timed exclusive, like the Metal Gear games, but this is looking more permanent, which sucks. A lot of my friends only have PS3's and the 360 keeps getting exclusives with this stuff. I used to be a huge Sony fan before this generation of consoles, so I'd like to see their more loyal fans rewarded from time to time.
At least there's Little Big Planet.