I think a cool use would be some sort of high tech paintball game. Have objectives to hold with beacons, and a listening device on all players guns. You can earn points by holding certain positions. You could come up with some pretty fun/dynamic scenarios.
Yeah, that was my reaction - AR gaming would be the killer app.
Also, my wife works at a school that allows students to sign out of their classes into other classes. Beacons would be great for this - "student X is not in the room they said they'd be in".
