Google says its Wallet service is already used by millions of people. Many of them use the app to store credit card and customer-loyalty accounts on their phone, and then use near-field communications to pay for purchases in retail stores by tapping their Android phone on an electronic reading device. You can also use the service to shop online; some merchants let you pay for Internet purchases with your Google Wallet account, so you don’t have to bother giving your credit card information to a bunch of different sites.

The new micro-payment service is launching with  just three online publishers – Oxford University Press, Peachpit and DK (known for how-to and reference books, among other titles). A draft blog post, which leaked onto the web earlier this week, listed some other potential partners such as GigaOm and Motley Fool, but it suggested arrangements were not yet final.