Tony Stark in The Incredible Hulk?
 

Ain't It Cool News has posted a rumor about how the Iron Man/The Incredible Hulk cross-over might work (Possible Spoiler Ahead!):

So the scene that was shot was for the Hulk with General Thunderbolt who is very important to the Hulk. Anyway, Tony Stark meets with him - which of course is a straight prelude to the Avengers Movie.