TweetZ is a twitter sidebar gadget for Vista / Windows 7.
The TweetZ gadget docks comfortably in the sidebar. Balancing size, function and appearance has been a process of trail and error over the last month and while not complete, there’s enough here to warrant letting others try it. There are two sizes, a larger one when it’s not docked in the sidebar, and a smaller one for when it’s docked.
TweetZ works much like other Twitter clients. You can tweet and reply as expected. Click on the "What are you doing" button and the editing window pops up.

The license of this software is Freeware, you can free download and free use this social networking software.