Here's a screenshot:
According to Google, "If your online store is rated in Google Product Search, you have 4 or more stars, and you have at least 30 reviews, you'll automatically get seller ratings with your ads. What's more, you'll only be charged if someone clicks on the headline of your ad - clicks on the review link are free."
No official announcement from Google about a roll-out to additional countries yet. According to this page, ad campaigns must be targeted to the U.S. to appear with seller ratings extensions.
Optimising Digital Marketing Campaigns with Search, Social and Analytics
At SES London (9-11 Feb) you'll get an overview of the latest tools, tips, and tactics in Paid, Owned, Earned, Integrated Media and Business Intelligence to streamline your marketing campaigns in 2015. Register by 31 October to take advantage of Early Bird Rates.