Windows Phone MarketPlace Now Supporting Uploading Multiple Versions of Apps to Marketplace (OS Version Dependent)
A recent change to the Windows Phone App hub now allows developers to upload multiple different versions of a single app to the marketplace; where only a single version will be available to the user depending on his device (ie: WP7 version, WP8 version). These changes will help the developer change the app description/metadata for one version of the app without confusing users of the WP7 version (Example: enabling lock screen updates for users, screenshots about that update and changelog will only be visible to users with a compatible WP8 device and not to users on WP7).
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.