Last night I cut over a few WP7 7.0 applications using the AdControl to 7.1 (Mango). In the process I lost the AdControl on all the application pages. No error, not complaint just an empty place where the AdControl should have been. If I was paying close attention I could see a brief flicker of the outline of the AdControl as though it was loading.
Todd, Matt and I have been working with SharePoint and Windows Phone 7 a lot lately. There are a lot of great scenarios for connecting Windows Phone 7 to your SharePoint farm. The phone platform provides a great reach scenario for many SharePoint applications. Unfortunately Windows Phone 7 does not support NTLM in custom development scenario and that is the most common authentication scenario we run into with SharePoint farms.