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!

 

Your application should handle snapped, filled, and full views


Your UI should reflow smoothly and gracefully as you transition across states
Your UI should also remain functional when in snapped mode; it might not have every detail that a full view will have, but it should be functional
When in snapped mode, focus on content that is relevant and needs to be visible. Avoid the common pitfalls in snapped mode, such as cramped, non-functional app bars, clipped content, or panning in the wrong direction (horizontal)

Reference (HTML)

http://msdn.microsoft.com/en-us/library/windows/apps/hh465371

Reference (XAML)

http://msdn.microsoft.com/en-us/library/windows/apps/hh465371