IDC announced today that mobile shoppers will account for 28% or $127 billion of the $447 billion the National Retail Federation (NRF) predicts U.S. consumers will spend this holiday season. “More than one third of smartphone-carrying consumers (who represent 24% of all U.S. consumers) are ready to use their mobile devices in ways that transform how they shop everywhere and, in particular, how they shop in retail stores.”