SEO resellers ask us constantly if social media helps your organic rankings. I've blogged on this topic quite a bit here on the HubShout blog. And as you know, the HubShout reseller program has been pushing deeper into social media marketing over the last year based on reseller feedback. But the big question remains:
Does social media directly impact organic search engine rankings?
Here is a short little video in which Matt Cutts basically says "no, not directly - but social media marketing is a REALLY good idea anyway and might help indirectly."
I agree 100% percent with this clip. In all my research I have not been able to uncover a clear case where social media helps organic rankings in a direct fashion. In other words, it's not really a link-building technique. That being said, social media marketing is a fantastic way to generate buzz, real traffic and reach a real audience. While it may not boost your backlink count, it WILL help you reach a wider audience and generate leads for your business.
In summary, social media marketing should be thought of more as marketing and less as SEO. It is extremely valuable and you should be doing it. But don't expect your organic rankings in Google to jump as a result.