At Internet Librarian this year, InfoToday mounted a couple of geolocation games. They invited attendees to check in with FourSquare, and also to log the QR codes scattered about the conference signboards to become eligible for prizes like an iPod Touch.
Most cell phones today have the ability to “know” where they are, and to interact with those places and nearby objects. Some librarians are putting this to use by setting up their libraries as a “venue” in FourSquare, leaving “tips” for those who check in there , and offering prizes to those who check in often enough to become “mayors” of their library.
My library hasn’t gone that far yet, but I can see it happening within the next year. It would be fun to create a geocache or some kind of recognition for “mayors” of the Central Library. I promised Boss I’d work on the geocache with a colleague after the first of the year.