From the Windows Vista Team Blog, I learned of Witty, a Twitter client for Vista. The software, powered by the Windows Presentation Foundation built into Windows Vista, runs like a "real" application and like some apps, can be minimized to the system tray. Like most Twitter apps, Witty lets you post updates, view timelines, view replies, respond to direct messages, and open links in your browser. However, Witty has some more unique features that make it stand out like the skinning capabilities, fade techniques, spell checking, the ability to remember the window location & size, and a whole bunch of keyboard shortcuts. You can download Witty here.