Here’s how it works: iBeacon allows iPhones to locate their position in space with centimeter precision. It does this by using the phone’s Bluetooth Low Energy radio to listen for the radio-frequency cries of various “beacons” that retailers must place throughout their store. With such a positioning system in place, store owners can designate certain areas in their shops — as small as tens of centimeters across — where actions can be triggered, like sending more information or a promotional offer to a customer’s phone. Christopher Mims
Sounds like something right out of Minority Report (the movie that is, not the original short story). And it’s here literally right now, without expensive facial recognition, without embedding microchips in our arms and, fortunately, with the freedom to opt-out whenever we want.