WordTwit is a plugin that uses the Twitter API to automatically publish tweets about new posts on your WordPress website, and is configurable with has
WordTwit keeps track of when you publish new posts, and automatically informs your followers by pushing out a tweet to twitter in the format you specify. All links are automatically converted to tiny URLs to save space. Most users see a substantial increase in blog traffic after tweeting their posts on a frequent basis using WordTwit.
Also check out our professional mobile plugin for WordPress, WPtouch.