Google announced on its Webmaster Central blog that they are now supporting rich snippets for ecommerce sites.
Rich snippets provide the ability to display structured data from web pages. Google's new ecommerce format will enable merchatns to show price, availiablity, and product reviews on pages offerings products for sale.
Merchants can show the information needed for product rich snippets by either providing a merchant center feed or add markup to their site. Since most ecommerce sites already provide Merchant Center feeds for use in Google Product Search, the majority of the neccessary work is already done. To make use of Merchant Center feeds for rich snippets, Google advises using the rel=”canonical” link element on product pages. By doing so Google can match the URLs in your feed to the pages found by its crawler.
The feature is currently only available to merchants located in the US, but Google will be rolling it out in more markets soon.