I noticed I get a lot of Twitter updates regarding bloggers publishing new blog posts, so I figured there must be a WP pluging to do so. A quick search turned up Twitter Updater:
The Twitter Updater automatically sends a Twitter status update to your Twitter account when you create, publish, or edit your WordPress post. You can specify the text for the updates, and also have the option to turn the auto update on/off for the different post actions in the admin panel.
Follow the directions in the post and enter your Twitter username and password under ‘Manage->Twitter Updater’ in your admin panel. You will probably want to turn off updates for “New Post Created” and “New Post Edited” because those could result in some noise if you change your mind.
Read the full post here