Twitter Audio 1.0 Free Download
Shareware: You can try this program, but this version has some limited features or time usage restrictions. You should purchase it in order to remove those limits.
By Twitter Audio you can record audio from your microphone. Then you can write some text (max 110 carachters) and upload them to Twitter. The tweet will be: "text + file url". File url is the URL of your audio file.
.NET Framework 3.5, DirectX