From this Monday Google release the software update that enables the payment system Google Wallet on Nexus S 4G phone on Sprint.
Introducing Google Wallet
Right now Google Wallet only works with Citi-Mastercards and Google Pre-Paid Cards. Visa and Google also announced an agreement to support Visa payWave app, but it is up to the financial institutions and banks to add support for transactions.
First Google Wallet user
If you want to receive more information about the availability of Google Wallet for other phones can register your email on the following link: google.com/wallet/get.html