Personally... I'm a fan of console exclusivity... to a degree. But thats a different story.
With that said... I think that Fallout 3 - a NON-EXCLUSIVE GAME having the DLC only launched for PC and 360 is absolutely unacceptable. I don't understand why Bethesda is doing it, but it's just kind of insulting.
I own a 360 and a PS3, and I have FO3 for the 360. But I still think PS3 owners deserve the DLC as much as anyone else. There's really no reason for them not to release it.