The Microsoft design language (formerly known as Metro) is the touch-and-tile UX language that Microsoft designed to create an interface focused on content, information, and movement. It is designed to embrace those principles: clean, light, fast, open aesthetics; dynamic, moving transitions and interactions; embrace the beauty of typography; content-focused interface; and authentically digital design. This new tiles interface is now on Windows 8, Windows Phone and XBOX.
Microsoft has finally realized its 3-screen strategy and this is a game changer; if you plan to work on creating software for the Microsoft platform, you need to become familiar with those UX principles. Find below some links that will be helpful:
MSDN: UX guidelines for Windows Store apps
MSDN: Windows Phone General Design Principles
And as soon as you become serious about building your first app (for you or a customer), you NEED to read this document if you want your app to get certified with less trouble:
Windows 8 UX Guidelines for Windows Store apps
(316 pages of detailed user experience guidelines!!!)
The touch guidance and links on my previous post are still valid: