Sprint and Google announced the rollout of Google Wallet to all Nexus S 4G customers, an app that enables consumers to transform their phones into their wallets and make purchases by tapping their phones at the point of sale (POS).

Sprint is the first carrier and Nexus S 4G is the first phone in the United States to deliver Google’s solution. The new service currently only works with Citi MasterCard accounts and Google Prepaid MasterCard and is available at “hundreds of thousands of participating retailers, including American Eagle Outfitters, the Container Store, Macy’s, Foot Locker and Subway,” according to a press release.

Google Wallet requires users to set up a Google Wallet PIN that must be entered before making a purchase to prevent unauthorized access and payments.

“Shipping Google Wallet to Sprint is a crucial first step in creating a new way for people to use their phones to make shopping faster and easier,” said Osama Bedier, vice president of payments at Google, in the press release. “The world is on the brink of the next big shift in payments, and today’s announcement demonstrates that we’re making real progress in attaining the vision we share with our partners for a new and innovative mobile payments platform. We believe this is just the beginning of a transformation that’s soon to come.”

Eligible Sprint Nexus S 4G customers will be prompted to download the latest version of the Android software. Once this download is complete, customers can launch the Wallet app to try it.

Google said yesterday that it will add additional partners to its Mobile Wallet service in the near future. The company has received NFC specifications from Visa, Discover and American Express, meaning users will be able to add those cards to their mobile wallet soon.

Sprint has teamed with Google in deference of signing on with Verizon Wireless, AT&T and T-Mobile in the ISIS initiative, which also aims to enable NFC-based mobile payments. ISIS promises trials in limited markets by mid-2012.