Recently the folks from MS answered a very frequently asked question, and their answer is copied below.
When you publish a Windows Phone ‘Mango’ update to an application you had previously published, the following will occur:
- The WP 7.0 version of your application will remain available to all users on WP 7.0 devices.
- The WP ‘Mango’ version of your application will be available to all users on WP ‘Mango’ devices.
- WP ‘Mango’ users who previously installed your application will receive an update notification. This will occur even if they installed your application prior to updating to WP ‘Mango’
- WP 7.0 users who have installed your application, but not updated to WP ‘Mango,’ will not receive an update notification.
- The WP7.0 rankings & reviews that your application received will attach to your new updated WP ‘Mango’ version too.
- The application metadata and screenshots for Windows Phone Marketplace submitted with the WP ‘Mango’ version of your application will be shared across both the WP 7.0 and WP ‘Mango’ versions of the application; i.e., a single set of metadata and screenshots will appear to both WP 7.0 and WP ‘Mango’ users.
- Once you have released the WP ‘Mango’ version of your application, you will no longer be able to modify the previously released WP 7.0 version of your app. We realize that some of you may worry about this limitation, and so we’re actively working on ways to mitigate it. To improve the experience for users, it’s our preference not to have “duplicate versions” of your apps in the marketplace. We are also going to work hard to encourage our pre-existing users to enjoy the free upgrade to Mango as quickly as possible.
As you can see, we have a problem here! There is no way to update a pre-mango release after you have released the mango update! Since the majority of users still haven’t updated to Mango there is a need for frequent update of the pre-mango versions.
There is a workaround though, you can publish the pre-mango app which is using mango components if the app detects that the mango is available on the phone! This is done using the reflection, so if you are interested, knock yourselves out! Read more about it!