Apparently, the plan for the app is to help ease the number one fear that users usually have in switching platforms: finding the apps they love. Microsoft is confident that the Windows Phone Store - which has around 135,000 apps according to the last Microsoft report - has enough apps to cover anything users would be looking for. So, the Switch to Windows Phone app would scan the apps on your Android device and let you know what is available in the WP Store, and what alternatives exist for the apps that aren't there.
The app search mechanism will be powered by Quixley. The rumor claimed that the app would be hitting the Google Play Store yesterday, but that didn't happen, but we'll let you know when it does.