Google +1 buttons have been available since March 2011 and are seemingly part of the Google social ranking criteria.
Google says: “Content recommended by friends (NDR Google account friends!) and acquaintances is often more relevant than content from strangers. For example, a movie review from an expert is useful, but a movie review from a friend who shares your tastes can be even better. Because of this, +1?s from friends and contacts can be a useful signal to Google when determining the relevance of your page to a user’s query.”
Read more athttp://searchengineland.com/its-here-google-1-buttons-for-websites-79394
Google+ is being tested by a restricted number of users. https://plus.google.comParticipating in Google+ may have an impact on SERP according to Danny Sullivan in his recent article : “being a brand on Google+ will mean people can make a direct connection to you, and that’s going to result in an increased chance that you’ll rank better for those people, when they’re logged in.”