We have had confirmation by the head of the Google spam team in a recent youtube video that said that Google pluses do not directly impact website rankings and we didn’t think so anyway considering that most social links are no follow anyway (no follow being that they are not counted by the search engines when ranking a website).
The use of social media is growing at an unstoppable rate and most people have a social media account rather than an actual website so why don’t search engines consider social signals when ranking a site? Maybe search engines do not have the technology at the moment to determine a legitimate link on a social media site opposed to a fake one. After all social networks are random places where users skip to one topic to the next sharing all sorts of stuff and people at times just will copy and paste stuff when sharing and talk in text speak that wouldn’t make much sense to people outside their social group thus Google and the other search engine will have a tough time determining whether someone is a bot or a real person. Social signals can be bought and manipulated but not only that are social signals really that powerful? How much effort does it take for someone just to “like” something just because their friends liked it? Does this really equate to a website being pushed up in the ranking over something else?
Social media in some circumstances like when something goes "viral" can bring in a lot more traffic and conversion than SEO can in a lot less time. When something spreads on social networks it has the potential to send thousands of people, but you have to keep in mind that only certain things can go viral and not everything and that you may only get teenagers and whoever else use social media come to your site and it isn’t always as targeted traffic as opposed to some one actively trying to find something on a search engine.
In the future social signals may be considered but at the moment social media is very important source of traffic but will not directly impact on your SEO.