Since Google isn't satisfied with just knowing everything about your interests, business, and personal and social life they want to track your spending as well. And since Google Checkout wasn't wildly popular and accepted like their search engine and mail, they'll reattempt with their new Google Wallet. The Google Wallet holds digital versions of your credit cards, rewards card and soon, transit cards in a password-protected app. It works anywhere a MasterCard PayPass is accepted, but is only currently available on a Sprint Nexus S 4G.