In the comics, "Spider-Man" villain Norman Osborn (Green Goblin) becomes a public hero after stopping an alien invasion. He uses his new status to replace The Avengers with supervillains, with he himself taking the Iron Man suit, which he takes from Stark Industries and designs to represent the recently-killed Captain America.
Spider-Man is owned by Sony, which makes it hard to believe that we'll see Osborn show up in Iron Man 3, but who knows. Keep an eye on this movie. If it keeps bringing surprises like this, it'll be a shame to miss out on.