Waiting to see Tony Stark appear in Thor or The First Avenger: Captain America? You might want to save yourself the disappointment; director Jon Favreau has confirmed that movie audiences won't see the character again until 2012's Avengers.
MTV's Splash Page blog caught Favreau's appearance on LA radio, where the director said that Robert Downey Jr. would not make a cameo appearance in either of Marvel Studios' next two movies - and then went on to express his admiration for the task of making Avengers work:
I'm not sure where 'The Avengers goes... There is no shooting draft written yet. It's gonna be a big undertaking for Marvel to actually incorporate what happened in 'Iron Man,' 'Iron Man 2,' 'Thor,' 'Captain America' [and] 'The Hulk.' All that has to inform one unified vision in 'The Avengers.' It's a very exciting prospect. And certainly, Tony Stark is not going to be involved in any of the movies until that one.
No shooting draft written yet? I wonder if that ties into rumors that unconfirmed-but-come-on director Joss Whedon will be rewriting the script...?