In the most recent Web Master’s video, Matt Cutts asks himself if there is any advice he would like to change from what he said in the past. He then goes on to explain that Twitter can play a roll in ranking factors for organic search results and that how reputable a twitter account is, is a factor in their algorithm. All of us in SEO knew this was coming, but to hear it from the horses mouth is worth talking about.
He does not go into which factors they look at but it can be assumed that number of followers and number of retweets are factors. We at Front Street Consulting don’t think each and every tweet is factored into the algorithm, just those from highly reputable users and accounts.
Here is a link to the video: