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!
Pans and scrolls in single axis to create sense of stability
Panning helps users navigate through a view that does not fit (horizontally or vertically) within the viewport. There are a lot of factors to consider when panning, for example: device type, orientation, input type (such as mouse, touch, or pen), etc.
Provide a sense of stability within your views by always scrolling on a single axis. You can change the axis if the device orientation changes, but ensure that there is stability and intuitive panning within the view.
For more details, here are the complete guidelines for great panning.