Like dozens of other brick-and-mortar retailers, Nordstrom wanted to learn more about its customers — how many came through the doors, how many were repeat visitors — the kind of information that e-commerce sites like Amazon have in spades. So last fall the company started testing new technology that allowed it to track customers’ movements by following the Wi-Fi signals from their smartphones.

via Attention, Shoppers – Store Is Tracking Your Cell – NYTimes.com.