WordTwit by Brave New Code is a plugin for Wordpress blogs that Tweets all you blog posts. Brave New Code does WordPress Design and Consulting and Theme Development. Check out their Design and Development Website Portfolio.
Using WordTwit saves you from Tweeting each blog post. If you are not already Twittering all your blog posts you will see a increase in your blog traffic.
The current version 2.0.10 requires Wordpress 2.6.x or higher. With version 2.x you can choose include or exclude posts to be Tweeted by tag or category. To shorten your URLs you can choose between tinyurl.com or bit.ly and if you like you can have WordTwit use your blog domain. I like the option of using your own domain as it helps with branding your site. Here is an example of using your own domain to shorten URLs.