I think the best way to describe this service is Froogle combined with Yahoo Store & Paypal. It's not opened to the public yet, but there are some vendors beta testing.
We're starting with a very small number of sellers and we expect to include more over the next several months. If you're a seller and you're interested in getting an announcement when this feature is generally available, let us know. And if you want to know how this functionality relates to Google's broader work in payments, read this update. We hope this feature will make it even easier for people to use Google Base to post and distribute a wide range of content, whether information for sharing or goods for sale.You can read the official blog post here.