One could safely assume that everyone reading this remembers the hubub that surrounded the cameo of Samuel L. Jackson in Iron Man, which hit theaters just over a month ago. Marvel Studios and Paramount went to great lengths to keep anyone from spoiling the surprise, including cutting the final post-credits scene from advance screenings to keep both press and early audiences in the dark.

But now, with the release of The Incredible Hulk less than a week away, they seem to be changing course a bit, revealing another highly anticipated cameo in a TV spot. Yes, the rumors are true, Robert Downey Jr. does make a cameo as billionaire superhero Tony Stark. And as you will see from the clip below (which does contain mild spoilers, by the way), his cameo isn’t going to be post-credits:

I suppose the question here is why they decided to release such a clip with the rest of the marketing materials. Why wouldn’t Marvel want to keep the nature of Stark’s cameo under wraps, so as to give audiences a pleasant surprise. I have two theories:

One is that they are trying to use the success of Iron Man to help propel The Incredible Hulk, playing on the nostalgia that many fans may have for the dry with of Downey as Stark. This could show a bit of worry about the box office, but I doubt it — with Hulk, they have little to worry about. The franchise alone, combined with the success of Iron Man should be enough to bring in the $$.

My second theory is that there is a bigger cameo at play in this film. We have already reported the rumors that Captain America may make an appearance, but that is very doubtful. I would guess that we have not seen the last of Sam Jackson as Nick Fury, but I wouldn’t be surprised if another famous character from the Marvel Universe shows up unannounced. Then again, this is all just speculation.

Sound Off: If Stark’s cameo isn’t the big surprise in Hulk, then who else do you think might show up in the film?