Michael E. Cohen for TidBITS:
That’s ironic, because the point of iBeacons is to help you find things — or, rather, to help your iOS device to find itself. iBeacons is the general name for a set of additions to the Core Location framework that developers can use when designing apps: it isn’t a new piece of hardware, nor a new app, but a capability. Apps can use iBeacons to answer the question “Where am I?” not in terms of a location on a map, like GPS does, but in terms of where the device is relative to another device. Specifically, where it is relative to another device acting as an iBeacon.
Think of an iBeacon as a tiny radio you can put almost anywhere. When your iPhone or other iOS device gets within range (a few dozen feet or so), it detects the iBeacon and can estimate how far away it is. Each iBeacon has its own identifier, too, so if your iPhone is within range of more than one iBeacon, it can tell them apart.
It’s all of the cool sensors in iOS devices that is beginning to attract me to the platform. I think you can do some really cool stuff in the classroom with iBeacons.