The first video in the new series of Google webmasters videos is about how PageRank flows from Twitter and Facebook in Google web search rankings. I recommend you follow @googlewmc on Twitter (that’s the official account for Google Webmaster Central) So when new webmaster videos come out you will be the first to know. I have just got this news from Matt Cutts blog.
How PageRank Flows from Twitter and Facebook in Google web search rankings
