What is the purpose of the GUID in a WP7 application?

Question

What is the purpose of the GUID in a WP7 application and can they be changed with ease?

Answer 1

The GUID is used to identify the app on the phone and in the marketplace. After acceptance in the marketplace, a new GUID will be assigned to your app by Microsoft so you should always use that GUID from then on so that your upgrades etc will target the same app.