Microsoft wants to patent an app migration service that would have a few different layers of functionality. First off, it could analyze what apps you have installed on, say an Android device (Microsoft even uses this example in its patent application). Then it would search for identical or similar apps in the Windows Phone Marketplace, present you with suggestions, and let you buy and install every app you want to with one click. In case an official app isn’t available in the WP Marketplace, this would presumably suggest well-performing third-party alternatives.
What app problem? Microsoft is developing a service to migrate all your Android apps to a new Windows Phone » Unwired View