Peter Kuhn (aka Mister Goodcat) - who recently got the Microsoft Community Contributor award and is the trainer on our upcoming XNA training - blogs about the recent updates in Mango allowing to mix Silverlight and XNA content in the same application.
Source: Mister Goodcat's Blog
One of the exciting new features of the Mango update for Windows Phone 7 is the possibility to mix XNA and Silverlight content in the same application, which is an extremely useful and effective feature to both enrich your Silverlight applications with advanced graphics as well as building fancy UI experiences for your XNA-based games. In this screencast I'm walking you through a sample application and explain all the important involved code required to achieve this integration of XNA and Silverlight on Windows Phone 7 "Mango".