This has been possible in Japan and other countries for years, but it appears it's now becoming more widely available in North America:
http://www.nytimes.com/2010/04/29/technology/29cashless.html?hp
A new iPhone/iPad/iPodTouch app called Square (https://squareup.com/) available next month allows you to accept payments with a cellphone, and PayPal has a cellphone payment application that allows you to bump two cellphones together to complete a payment.
http://www.nytimes.com/2010/04/29/technology/29cashless.html?hp
A new iPhone/iPad/iPodTouch app called Square (https://squareup.com/) available next month allows you to accept payments with a cellphone, and PayPal has a cellphone payment application that allows you to bump two cellphones together to complete a payment.