Do you take cellphone?

PayPal, the online payment-processing system made popular by eBay, its corporate parent, is betting that its future may not be online, but in the real world. PayPal is planning a push into retail stores with a system that would involve swiping cellphones at registers to make payments, rather than using credit or debit cards. The company, which has 95 million users online, estimates expanding into physical stores could double its revenues to $7 billion within two years.

PayPal isn’t the only firm anxiously eyeing this market. Google and Apple are now reportedly working on cellphone payment systems—using a technology called near-field communications—as are cellphone makers like Research In Motion and Nokia. The systems could be useful for consumers who always have a smartphone in hand. But for cellphone companies looking to be the next Visa, it’s a market potentially worth tens of billions of dollars.