This plugin places the official Twitter Tweet Button on your posts, pages or shortcode. Based heavily on Tweetmeme.
Easily allows your blog post or page to be retweeted. It provides a live count of how many times your post/page has been retweeted throughout Twitter. Currently being by SocialBrite and other members of the social media community.
Live count of tweets from Twitter
Allows you to change the source which you retweet, e.g. " via @yourname"
Easily installation and customization
Better integration, allowing custom titles, related accounts
Integrates with WordPress MU