Google Wallet is an application service google used to make payments easily through a cell phone. This service enables mobile phone owners pay and disburse coupons via mobile phones with the Android operating system. Google's own technology Wallet current (May 2011) only available on the Nexus S 4G mobile phone operator Sprint Nextel. Google Wallet uses a technology called near field communication (NFC) or short range communication that allows users at the checkout to pay via mobile phone equipped with NFC.
In addition, Google Wallet will only support credit cards from Citibank MasterCard and Google Prepaid Card. But later, this service will be open to any kind of payment card and will be launched in five cities of New York, San Francisco, Los Angeles, Chicago, and Washington DC.
Source : http://id.wikipedia.org/wiki/Google_Wallet