No extra scene for me either. But, I was busy at the drive-in watching Super 8 on the other screen behind me as soon as the credits were rolling. (Still, I think I would have noticed another scene.)
It's the first x-men movie that I've seen & I was pleasantly entertained. Apparently there were things you "should have known" if you were a fan of the series. My wife kept asking me questions about that - things she picked up that were absent in the script, but that she thought should have been known. Basically, at the end of the movie, she didn't have a clue if Magneto was a good guy or a bad guy. Are they all good guys, 2 teams? All bad guys? She was lost.