As I previously mentioned, I've written a small C# application called "Twitterbot" that grabs items from an RSS feed and retrofits them for twitter. After discussing it with some of the folks over at twitter, they have no problem with me open sourcing the litte bot, so I give you, the Twitterbot.
I also added a few fixes this morning after adding the hybridized twitter-thing:
Improved duplication checks
Refresh slow-downs between 12:00 and 6:00 am (exclusive)
Better error handling
A few comments :)
The Twitterbot can be downloaded from the subversion repository, details are located on the Twitterbot's page. The Twitterbot is BSD licensed and will run with both .NET and Mono. Enjoy!