jfruh writes "Call it Google Analytics for physical storefronts: if you've got a phone with wi-fi, stores can detect your MAC address and track your comings and goings, determining which aisles you go to and whether you're a repeat customer. The creator of one of the most popular tracking software packages says that the addresses are hashed and not personally identifiable, but it might make you think twice about leaving your phone on when you head to the mall."
