Originally Posted by vince128 People claimed that Google will use this as one of the social metrics to rank your site in the SERP. There was one case study in particular (either by Mashable or Technorati) indicated this very early on.

This has been happening for quite some time. Most Google+ users will have noticed by now that any site that has been shared (+1'd) by their connections on Google+ will now appear much higher in their search rankings on Google.