Google and Bing both just confirmed that both Twitter and Facebook do impact SEO rankings! It’s been suspected for some time but now they’ve both announced how!
Bing: We do look at the social authority of a user. We look at how many people you follow, how many follow you, and this can add a little weight to a listing in regular search results. It carries much more weight in Bing Social Search, where tweets from more authoritative people will flow to the top when best match relevancy is used.
Google: We do use it as a signal. It is used as a signal in our organic and news rankings. We also use it to enhance our news universal by marking how many people shared an article.
You need to be on Twitter and sharing content that gets retweeted!
Bing: We calculate the authority of someone who tweets. For known public figures or publishers, we do associate them with who they are.
Google: We do compute and use author quality.
Bing: We calculate whether a link should carry more weight depending on the person who tweets it.
Google: We also use this as a signal, especially in the “Top links” section [of Google Realtime Search].
You need to be actively building your follower base and improve your “author authority” (so your tweets and retweets of your tweets help you more and carry more weight).
Thanks to these comments, we now know that those link sharing activities on Twitter + Facebook are evaluated based on the person/entity sharing them through a score Google calls “Author Authority,” and Bing calls “Social Authority.”
If you aren’t yet on Twitter or Facebook (with a Fan Page) you need to get going – it’s only going to become more important as time goes on.