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!
Designing for touch will get you a long way in Windows 8. As you lay out your screens, you should test on lower resolution (1024×768) and ensure that your application works well with the soft keyboard.
Ensure that the keyboard is not pushing fields too high or covering controls that users will need in order to navigate through the app (such as submit buttons).