In an effort to make developers' lives easier and help avoid end user confusion, Microsoft has added an important new feature to the Windows Phone Dev Center. Developers can now submit multiple XAP files per app GUID (i.e. multiple versions of one app) to target different versions of the Windows Phone operating system more effectively.
In the post over at the Windows Phone Developer Blog, Bernardo Zamora outlines the new feature and how developers should go about treating their apps with respect to Windows Phone 7.5 and Windows Phone 8 users. One of the advantages of the feature is the ability to enter unique descriptions per XAP file, meaning you can now accurately describe the WP7 features in the 7.1 version of the app and the WP8 features in the 8.0 version of the app:
One of the key advantages of multiple XAPs per app GUID is that you can associate different metadata, such as long description, with each XAP. [...] And you don’t have to worry about your app showing up twice or end users finding the wrong version for their device. Our catalog detection will show your 7.x app to those with Windows Phone 7 devices and the 8.0 app to those with Windows Phone 8 devices.
This change also extends to global app publishing and the submitted screenshots pertaining to each version. The overall benefit to the developer is that there are less app entries to juggle, while the end user just sees the version of the app that is applicable to them. In other words, it's avoiding the Angry Birds Space/Star Wars predicament (as pictured above).
If you're a developer, we recommend you read the entire post by Zamora which offers a ton of screenshots of exactly how to manage multiple XAP files per app GUID. Zamora also reveals that the most common submission error you might run into while attempting to do this is by updating a WP7 app to a WP8-only app. Read the entire post here.
Source: Windows Phone Developer Blog