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!

Metro, Metro Design, Windows 8, User Experience

Present errors to the user in a non-obtrusive manner and ensure your messages are actionable. Follow the guidelines for error messaging and choose the appropriate UI surface to present the errors.

Reference (HTML)

http://msdn.microsoft.com/en-us/library/windows/apps/hh465304.aspx

Reference (XAML)

http://msdn.microsoft.com/en-us/library/windows/apps/hh465304.aspx