Collider recently talked with Don Cheadle about the upcoming Iron Man 3 and The Avengers:

"Q: Are there any future Marvel movies that you might be appearing in?

DC: Well the Iron Man 3 is coming back. We'll probably do that again in February and there's talk of a War Machine spinoff, which I guess, unless I get recast, I would probably do.

Q: Will you be in The Avengers?

DC: Not this one that they're shooting right now. Thank god!

Q: Was that ever in the works?

DC: Me being in The Avengers? I have a contract to be in The Avengers but I'm glad they haven't exercised that option yet. I need some down time."