Any true FPS gamer knows mouse + keyboard is the only way to go.
Why do you think microsoft doesn't let Xbox live play with PC? It is not a technical issue. It is because PC gamers (with mouse and keyboard) would have the upper hand and make the game un fair.
Microsoft did toy with PC / Xbox cross over game play, was it Shadowrun (cant remember off the top of my head, but it might have been called that) , i remember edge doing an article with the developer team about how much of a headache it was to get the balance right because Keyboard/mouse players, even in the hands of a novice at gaming, could completely devastate even a professional gamer playing on the Xbox, the responsiveness of keyboard and mouse, and the precision completely overruled the console players skill.
They had to introduce all sort of auto aim features for the console version and add an artificial "lag" to the PC version to even things out.
Even now, FPS games on consoles have a large amount of "auto aim" going on in the background because of the massive inaccuracy and slow reaction a gamepad has when put against a mouse.
Now... looking to the future, the PS move , if they get the other controls right for being able to move and look around , will be as good ,if not better than a mouse for aiming... as your actually, aiming.
(Killzone 3 fails at the looking around mechanism sadly having to use the edges of the screen to turn around left when you want to be aiming at something on the right is annoying as hell , but gets so much more right)