Following up on our digital wallet discussion yesterday, CWmike writes "Google officially launched its Google Wallet application today for NFC-ready Sprint Nexus S 4G phone users. The application launches initially for Citi MasterCard credit card holders, but Google also said today that Visa, Discover and American Express will be able to add their cards to future versions of Google Wallet. The application, first announced in May, was described in an official blog post. Visa said in a separate statement that it has licensed Google to use Visa's PayWave technology, used in 'hundreds of thousands' of terminals worldwide. But Visa didn't describe a timeline for when that function would be enabled. Google said it will allow users to add any bank card to a Google Prepaid Card and they will receive $10 to try the service." Reviews of the service are popping up, and many seem to say the same thing; when it works, it's great, but your real wallet isn't going anywhere.