Online sellers have been able to place Google Checkout "Buy Now" buttons on their websites, but - until now - the buttons only allowed buyers to purchase one item at a time. The new Google Checkout shopping cart allows buyers to add multiple items to their shopping cart, change item quantities, and remove items, all without leaving the seller's website. When buyers are ready to check out, they can complete their purchases with Google Checkout. To see the cart in action, check out the Demo Store.

In related news, Google Product Search unveiled a new categorization system for describing product types. Product_type is an optional attribute that sellers can use to indicate the category (or categories) of the product being sold. The Google product taxonomy is a tree of categories that describe product families, with verticals (Electronics, Home & Garden, etc.) at the highest level, followed by more specific product families or products within these broad categories (such as Electronics > Audio > Audio Players & Recorders > MP3 Players).