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!
Supports landscape and portrait views
Rotation allows users to optimize interaction with your app with optimal comfort and ease of use for their device. Windows 8 gives you multiple choices for rotation: free, constrained, and combined. Implement as many of these choices as is appropriate for your app.
If your app does not support every possible device orientation, declare that in your manifest and plan accordingly. You don’t want your user to get into a non-functional state in your app from changing the device’s orientation.
To learn more about rotation, check the rotation guidelines.