Give this article a read:

http://n4g.com/user/blogpost/pixelsword/527895

It pretty much convinced me 100%, but then again I was never against the idea.  Some Playstation games play with PC, PS3, and PSV gamers so I think Sony might get on bored eventually if a third party could make a good argument.  However I don't really think MS would agree to this any time soon since it would probably make them look bad and even more generic.  Nintendo is a wild card in this, and honestly they have a lot of online catch up to do before they are really even relavent in this conversation.

Quite frankly, I don't really want to see this happen for many PC games. Mouse and keyboard offer a vastly different way to control games, and often that difference is for the benefit of PC gamers. I'm afraid there would be annoying balancing issues (as in, console gamers getting potentially unfair compensation for using a controller).