Official Google Blog: Doing more with the +1 button, more than 4 billion times a day

Including schema.org snippets, as explained here

In June we launched the +1 button for websites, making it easier to recommend content across the web. In July, the +1 button crossed 2 billion daily views, and we also made it a lot faster. Today the +1 button appears on more than a million sites, with over 4 billion daily views, and we're extremely excited about this momentum.
It's just the beginning, however, and today we're launching two more features that make +1 buttons more useful for users and publishers alike.
Sharing with your circles on Google+
Clicking the +1 button is a great way to highlight content for others when they search on Google. But sometimes you want to start a conversation right away—at least with certain groups of friends. So beginning today, we're making it easy for Google+ users to share webpages with their circles, directly from the +1 button. Just +1 a page as usual and look for the new "Share on Google+" option. From there you can comment, choose a circle and share.

Official Google Blog: Doing more with the +1 button, more than 4 billion times a day