In Windows Phone 8 you can make your app resume instead of re-launching when you click on the app tile. This will also preserve the backstack of the application.
I've created a short blog post on how you can add fast app resume to your application.
http://mindre.net/Article/Windows_Phone_8_Fast_app_resume
I've created a short blog post on how you can add fast app resume to your application.
http://mindre.net/Article/Windows_Phone_8_Fast_app_resume