For now, only certain ads are eligible for the seller rating extension. Advertisers with a four star rating or higher and more than 30 reviews will automatically be included in the program. You must also be opted in to Google search and must be targeted to the U.S. only.

Other highlights of the Google seller ratings extension:

 Users can click through to see reviews. You won’t be charged for these clicks

Review sources include Bizrate, Reseller Ratings, ReviewCentre.com and Viewpoints, among others.

 You canopt out of seller rating extension by contacting Google. 

This new feature is sure to be greeted with enthusiasm by users, but it also poses a great opportunity for businesses as well. Star ratings introduce a new "stamp of approval” for ads that lend them legitimacy—and you’d better believe that an ad with four stars appearing next to an ad with no stars is going to get more clicks. So, now the challenge is to get enough good reviews to have seller rating extensions activated. There’s no real trick to achieving this other than providing excellent customer service. But you will need to make sure that your Google Product Search listing includes the correct business name, website URL and other information. You should also make sure your Google Merchant Center account is up to date and accurate as well.

The thing you should definitely NOT do is to begin posting fake reviews. For one, this is highly unethical, but more importantly, Google is more adept at spotting fake reviews than you might imagine. Instead, simply encourage your customers to write good reviews for you online if they are satisfied with your business. You can’t offer any kickbacks for their time, but a quick link in a thank you email or a mention in your newsletter can go a long way.