This is not too big of a surprise considering Iron Man and The Incredible Hulk had similar scenes after the credits to set up future Marvel Studios movie, but what is interesting is who the clip may be about. BadTaste.it alerted us they got the news...
There is a very juicy news about Iron Man 2 on BadTaste today. A 100% trusted source (NOT from the production/distribution, but very familiar with the movie) confirmed us today that there will be an easter egg in IM2. It's an extra scene, just like the one in the first movie, after the end credits. We are able to tell you what's about! It's a scene about... Captain America and Thor!
So while it's not officially confirmed, we would suggest not leaving Iron Man 2 until after the credits.