I\'ve seen the beautiful MetroTwit interface http://www.metrotwit.com/ ; I would like to know which WPF components have been used for trying to reproduce it.
Look at http://metrotheme.codeplex.com/ and http://www.silverlight.net/content/samples/sl4/themes/cosmopolitan.html those are silverlight but you can use it in WPF with some changes
MetroTwit designer here :)
All of the controls and animations were designed from scratch.
Obviously I drew a lot of inspiration from Zune, Windows Phone 7 but everything was re-templated from the default base styles. Most of the icons were made in Photoshop then converted into Expression Design to be output in XAML.
Since much of our design was with a Twitter client in mind, it's not universal for all applications. What you should really do is read up on the User Experience Design Guidelines for Windows Phone for a much broader understanding of Metro.
After you have a solid grasp of what you believe Metro to be, it's much easier to style the controls to the way that suits your application.