Tim Robbins is going to be playing Howard Stark in an important flashback sequence that is going to set up the Avengers and Captain America films. Jon [Favreau] wanted to get a good actor because he didn't think the guy who played Howard in the last film could carry such an important scene.This could make sense. There's already been some rumblings about Captain America in "Incredible Hulk." Too bad for Gerard Sanders, who played Howard in the first movie.
Nothing's been confirmed yet.
They also had some other rumors. Seems there could be a chance that Hawkeye and Black Widow could be in the movie as well. I seem to recall a call sheet for acting roles that had a female character that sounded like her. I'd absolutley love to see Hawkeye on the screen.