Backtype, which is a tracking tool for Twitter, has jumped into the influence game similar to what Klout does, and now provides influence measurements for Twitter users.
Backtype uses a proprietary algorithm which is similar to Google’s PageRank system to indicate how influential a (Twitter) user is. The score for a user is based on the examination of a user’s interactions and reach with friends and followers on Twitter.
Backtype has traditionally been a blog plugin to track Twitter trackbacks for URLs but this change definitely adds more value to the service. To check yours or any users Twitter influence, head over to http://www.backtype.com and type in the @username in the search box.