It is only natural that search engines are going to be looking at social signals to either influence search results or validate them.
All the search engines have either created or partnered with social sites, incorporating elements of them into their search results, and many conversations we have had with the engines indicates this will only continue as time goes on social communities continue to be the choice destination for web users.
Even as recent as March 2012, Maile Ohye from Google talks about getting social votes and shares as a tip to improving your SEO.
TastyPlacement recently put out a really nice Infographic that details some tests on how social signals impacted search results, which we are sharing below: