By now you’ve probably heard that Iron Man 2 contains cameos, of a sort, from Captain America and Thor. Though those soon to be filmed Marvel heroes don’t actually show up in the movie themselves, their weapons do. Thor’s hammer is supposed to be in an Easter egg which shows up during the credits. And then you’ll see Captain America’s shield, laying around in Stark’s laboratory (as it was very briefly in the previous film).
Obviously the details of these scenes are pretty major spoilers so if you don’t want to know more, click away now.