Google’s newest iteration of its Android phone OS will include a wallet that lets use your phone to make payments by tapping it against a cash register, CEO Eric Schmidt revealed Monday.

“This could eventually replace credit cards,” Schmidt said.

Android 2.3, codenamed Gingerbread, will be released in a “few weeks,” Schmidt said on stage at the Web 2.0 Summit conference in San Francisco. Schmidt showed off how so-called Near Field Communication would work using an unnamed smart phone he called an unannounced product. Using the software from Android and a NFC chip in the phone, Schmidt was able to “check in” to the conference, launching Google Maps, by touching the phone to a conference sign that had a built-in antenna.

(For geeks, there was little doubt Schmidt was showing off the “Nexus S”, a device thought to be made by Samsung as the successor to the original Nexus One. Unlike most other Android phones sold, the Nexus S will run the stock Android OS with no carrier modifications, making it the perfect phone for app developers and tinkerers.)