Google is rolling out a new feature through their Google +1 Button. They call it recommendations.
The idea behind this feature is to showcase your site’s best content when a visitor hovers the cursor over the +1 button.
This feature is now available to the Google users on Google Plus developers preview group. It would be rolled out to all the web users in the coming weeks.
Google spoke about this new functionality:
Today, we are rolling out a new feature of the +1 button in platform preview: when users hover over a +1 button, they will see recommendations for other great content on your site. To keep these recommendations more relevant and on-topic, they will always refer to pages on the same domain or subdomain as the +1 button.
Web publishers would not have to make any changes to the code on their web pages.