I saw 4 or 5 in the hour I was sitting around at Philly International today. A few at various hotels. A couple flights the person next to me had one. It really is the hardcore traveler's device.
I saw one at a restaurant. That was a little inappropriate, considering he was with someone and just staring at his toy while she babbled away, looking increasingly pissed at his inattentiveness. My girlfriend and I had a laugh at their expense, at least. 🙄