Read original post by Andrei Marukovich at LunarFrog
Prism library from Microsoft patterns & practices team is well known among WPF and Silverlight developers. It provides guidance for developing maintainable client software, helps with MVVM pattern implementation and facilitates good design practices, such as separation of concerns and loose coupling.
Recently, P&P team presented a version of Prism for Windows Runtime. This version of Prism is mainly focused on MVVM, navigation and app lifecycle management. Optimized for WinRT, it also supports such Windows 8-specific features as setting and search flyouts.