Kona http://konaguidance.codeplex.com/ is a project by Patterns and Practices aiming to provide guidance in the development of Windows 8
Metro, Modern UI, "Windows Store" applications.
Kona Contrib is a community based project which should supplement the P&P project with additional guidance on developing features that didn't make it and additional documentation provided by the community, e.g
Currently Kona Contrib is on waiting mode till the Kona itself is stabilized and released supposedly end of March.
So stay tuned.