Google Wallet has always been held back by two primary problems: a lack of devices that support the NFC-enabled app, and a limited partnership that only let customers use Citi MasterCards cards natively. That latter issue has been completely wiped out today: a new Google Wallet app is available now that supports all MasterCard, Visa, American Express, and Discover credit and debit cards.
It's not all quite as rosy as it sounds, however. There was a reason why those other cards weren't supported from day one: competing programs like ISIS. Google hasn't magically made agreements with all of these credit card companies; instead, it has changed the way Wallet works. With the new app, any cards that you use on Google Wallet online (once called Google Checkout) or in the Play store will automatically appear in the app. The credit card data, of course, is stored in Google's servers instead of the secure NFC chip on your phone. When you make a purchase, the merchant doesn't see your credit card information — unless you're using one of Citi's MasterCards — instead, a "virtual" Google Wallet MasterCard is used. With this setup you likely won't see your purchases on your credit card statement from merchants — they'll show up as a Google Wallet charge instead.
Despite the technical change, the bottom line is that almost anyone in the US can use Google Wallet as a true wallet replacement since it can now make charges with any credit card.
Google has also added a new security feature: users can remotely disable their Google Wallet phone if they lose their device. It's well-known that the service has had some security issues in the past, and it's nigh time that Google add this feature to the service.
The only major issue that the service has now is that only a handful of devices support the app. If you have one of those devices, you'll be happy to hear that the new Google Wallet app is available now in the Play store.