Might Tim Robbins play a role in Iron Man 2?
According to Latino Review, the actor would portray Howard Stark (Tony's dad) in a flashback sequence.
The site reports a scene "is going to set up The Avengers and Captain America films," adding that director Jon Favreau cast a well-respected actor as Mr. Stark because it's such an important moment in the movie. Robbins would certainly fit that bill.
Moreover, bow-and-arrow-wielding hero Hawkeye, plus the evil Soviet spy Black Widow with whom he falls in love, will appear in the sequel.