Delta has them in First or Business class on all widebodies and 737-800's. They are also in coach on the 737-800's.

Swissair now has them working on their longhaul flights, at least in First and Business.

United has them on a lot of planes, but they seem to be deactivated most of the time.

They are on other airlines, but I don't have firsthand knowledge on what aircraft they are deployed.