cylonlover writes: Online retailing leader Amazon is to make a compelling offer this coming Saturday – use their smartphone app to compare prices, and they'll effectively pay you $5 to walk out of the store. It is an historic move in the evolution of retail sales. Gizmag writes that, as smart phone penetration heads for ubiquity, the price comparison app might go mainstream quite quickly from here. For the customer, it means getting accurate comparison information before a purchase. For the shopping app provider it means an opportunity to make a bid on a customer's patronage at the time- and point-of-sale, inside a competitor's bricks and mortar, at the same time as creating a marketing intelligence tool par excellence.