I think I've seen two. Not sure if this girl in one of my classes had one, but I know I saw some other guy with one. Everyone else at my school has iPhones.
EDIT: Someone in my biology class has an S3. Make that two confirmed sightings. And I've seen one other person with a HOX besides me.
EDIT 2: At Universal Studios, the dude next to me has one. 3 confirmed.
Friend: Is that a banana in your pocket, or are you just happy to see me?
Me: Nah, it's just my HTC One X.