Google Wallet is a mobile payments application that leverages Google s Android mobile operating system and runs (for now) on the Samsung Nexus S 4G phone, available from U.S. carrier Sprint. At this point, Google Wallet only accepts the Citi Mastercard and a Google Prepaid Card (did these exist before today?!) Google Wallet will store multiple credit cards, offers, loyalty cards and gift cards, all without the Costanza wallet effect. Eventually, the Wallet will work with a wider range of phones and credit cards.
Source: https://threatpost.com/google-wallet-secure-what-you-need-know-052611/75277/