Great Vista/WPF Application - Yahoo Messenger

My US colleagues have been working with Yahoo to help create a new version of their Messenger product which takes advantage of Windows Vista and Windows Presentation Foundation. This looks to be coming along very nicely with some great UX (thanks to the simplicity of building complex UX with WPF) and some good use of Vista specific features such as Windows Sidebar. Check out the screencast at https://messenger.yahoo.com/windowsvista.php