You thought you were shopping for family and friends this holiday season, but in doing so you may have also given a nice present to retailers: your data.Over the past several months, a growing number of retailers -- including major chains Bloomingdale's, American Apparel and Brookstone -- have hired technology companies to help them learn more about what shoppers are doing in their stores. Spend 30 minutes trying on high-heel shoes, only to make a beeline for the coat rack? Foot traffic patterns like that might be looked at later. Or maybe you just wandered aimlessly around. That also could be interesting to the retailer.You may not always be in the dark on this. There are also some businesses, such as the Apple Store, which have installed sensors so they can alert you to special deals or products as you walk past them, if you have downloaded a certain app on your iPhon
