The study by Validas, a research firm that gathers data from phone bills, shows that Verizon subscribers who have smart phones (but not BlackBerrys) power through an average of 450MB per month, up more than double from last fall, before Verizon's Droid-branded Android line hit the market. In the same period, iPhone users averaged about 350MB of data consumption, while BlackBerry users across all carriers were averaging less than 50MB......