For what it's worth, I've seen absolutely no indication that Google takes social data into account when ranking results. They only show it as metadata on items within the original ordering.
Actually I saw an example of this twice earlier today. I did a search for some relatively common terms ("api debug" or something like that) and a friend's companies API came up on the first page. Hopped into incognito mode, was not to be found in the first several pages. Same thing happened not too long after, a friend's blog came up for a term, tried incognito, it was gone.