The newly-updated Metro-style desktop app for the Microsoft All-In-One Code Framework <http://1code.codeplex.com/>. It allows you to browse, download, and submit new requests for a variety of common (practical) programming tasks.
The app itself seems to be WPF/.NET, yeah. It's supply .NET samples, so I'd hope so!
In any case, this app is just as much Metro as Zune (for desktop) or any of the current WP7 apps. It's just a shame Microsoft haven't released any WPF themes for Metro yet... it will probably all come officially with WinRT/Win8.
This sample browser looks good. I will try it out sometime later.