Do you mean this, Jawib? (might be a spoiler): At the end, Magneto, now supposedly "cured," is sitting in the park with the other old men. In front of him is a chess board with metallic pieces. IIRC, he closes his eyes, extends his hand out to see if he can do it...and the chess piece vibrates.
I was arguing with my friend afterwards if the chess piece really vibrated, or whether the shaking credits made you think it vibrated. Either way, I don't know if they're ballsy enough to make an X4...
And Colossus is cool, but Archangel (at least I'm assuming that's who the winged guy was supposed to be...wish he had a bigger part) was pretty nice to look at.
edit: Oh, nevermind: "If you stick around after the credits, there’s another coda to the story – and it’s one that frankly baffles the shit out of me. It’s of Moira MacTaggart tending to a bandaged patient. Yes, it’s Charles Xavier, back from the dead."