As we reported yesterday, Google was said to be planning a launch for their Google Wallet service, and lo and behold, they did.  It was reported that they had MasterCard on board and now it looks like Visa, Discover and American Express will soon be join the team.  Both Visa and MasterCard have credit card terminals at hundreds of thousands of locations that will work with the wireless purchasing initiative.  Google said it was now working to include support for Visa, American Express and Discover accounts in future versions of the software.

The Google Wallet app will come out this week ad be available for download as an “over the air” update.  Unfortunately, unless you’re a Sprint subscriber and have the Nexus S 4G smartphone, you won’t be able to use the app.  Sprint was one of the original partners of Google in this endeavor, and it’s only befitting that they get to launch the service ahead of others, which is also a traditional move for Google and its partners.

Aside from Citi Mastercard credit cards, customers will be able to use a Google Prepaid Card for their purchases.  Early adopters of the service will be awarded a $10 bonus after setting up a Google Prepaid Card in the Google Wallet application.

Google’s release is seen as a preemptive assault on Apple, as the soon-to-be-launched iPhone 5 is rumored to have an NFC chip for mobile payment transactions.  Qualcomm was reportedly supplying the NFC chips to Apple and their “interest in NFC technology and e-payment systems has been evidenced by several patent applications, job postings and even claims made by Deutsche Telekom execs.”