The new version of WinRT XAML toolkit v1.5 is released and is now available for download from WinRT XAML Toolkit CodePlex page.
What is WinRT Toolkit?
WinRT XAML toolkit is an open source project which contains set of controls, extensions and helper methods for WinRT XAML Apps.
Note that the WinRT Toolkit is not a full port of the Silverlight Toolkit and the toolkit is currently based on Windows 8 and Windows 8.1 Preview SDK.
The WinRT XAML Toolkit 1.5 is currently in Beta and can be downloaded from CodePlex.