Here is a list of items that are tested in your Windows 8 App. If you are in Southern California, please email these posts for more information on getting a token for your app by June 30, 2012!
Content is primary navigation mechanism
A trait of a great Metro style app is content before chrome. When people focus on content, the composition of that content forms the identity of the application and it should become the primary navigation mechanism. Avoid tabs, menus for navigation, and home buttons. If your app needs navigation, you can use a header menu and section labels to navigate, or a navigation bar.
Check the guidelines for navigation design for Metro style apps if you need tips for your navigation.