Update: Google has now gone ahead and officially announced the launch of Google Wallet, complete with another video. Google VP of Payments Osama Bedier writes:

We’ve been testing it extensively, and today we’re releasing the first version of the app to Sprint. That means we’re beginning to roll out Google Wallet to all Sprint Nexus S 4G phones through an over-the-air update—just look for the “Wallet” app.

When we announced Google Wallet, we pledged a commitment to an open commerce ecosystem. We appreciate Citi and MasterCard for being our launch partners. And today, Visa, Discover and American Express have made available their NFC specifications that could enable their cards to be added to future versions of Google Wallet.

Google Wallet is launching today, it would seem. Google hasn’t made the official announcement just yet, but it’s expected anytime now.

MG Siegler got ahold of a document that were reportedly sent to partners. In the document, which he provides a picture of, it says:

Google Wallet is launching September 19, 2011. Google Wallet is a smart phone application (app) that allows owners of the Sprint Nexus S Android phone to use their smart phone as a wallet. This application or app will transform the way clients pay. Once Google Wallet is installed, the Sprint Nexus S phone may be used as a contactless (Tap and Pay) device at all PayPass enabled merchant terminals. Google Wallet is currently only available with Nexus S Android phones running Android Operating System (OS) 2.3.4 (Gingerbread).

Here’s the video Google provided back when they announced Google Wallet:

Here’s a teaser they put out a few days ago, featuring George Costanza from Seinfeld:

GigaOm found a Google Wallet logo on a MasteCard PayPass NFC reader at Peet’s Coffee in San Francisco, seemingly providing more confirmation that Google Wallet is launching.

More when the official announcement comes.

Until then, here are 43 things you should know about Google Wallet.