Marvel had a special on tv called Marvel Studios: Assembling a Universe where they went through the progression of Marvel movies from Iron Man up to current. Since they have just started filming the Avengers movie sequel, they couldn’t show or say much but they did show some concept art which showed Hulkbuster Iron Man fighting the Hulk. How awesome is that going to be!!!!
This could just be part of the plan to have the Avengers turn against the Hulk if he gets too savage and they have to send him out into space ala Planet Hulk. Heck, they could even have Rocket Raccoon meet up with the Hulk in a Planet Hulk movie. Things are looking better and better for an actual Planet Hulk movie.