Apple is taking a closer look at shoppers in its retail stores, under a new program that will push product-related information to their mobile devices using its iBeacon trackers.All 254 of the company's U.S. stores now employ Apple's iBeacon location services technology, Apple confirmed Friday. The iBeacon software was included in Apple's recent iOS 7 update for mobile devices like the iPhone, iPad and iPod Touch. Compatible iBeacon hardware has since been installed throughout Apple's stores, anywhere from the front entrance to a product table sporting the latest iPads, from which it communicates with the software.The integration marks Apple's large-scale entrance into the hot, emerging known location- or place-based marketing field. Over the past year or so a range of smaller startups have sprung up offering services designed to gather more information about shoppers in stores to serve