[m463]

...Unless you have a private wifi AP you connect to. Then your device is individually identifiable and trackable.

In addition, I believe apps that use ibeacon technology can respond to specific ibeacons. But I think your phone can become a beacon.

I suspect (but am not certain) that if your phone is running app XYZ it can talk to other phones running XYZ through the XYZ registered beacons (if location services are on for app XYZ).

Also, just for an interesting example of where some of this stuff can go... The target app will change the price of an item if it finds you are in a store (search "target app price switch").