Developing for Windows Phone 7? Want to make advertising supported revenue straight from your app? Microsoft has released SDK for that ;) You can download it here: http://go.microsoft.com/fwlink/?LinkId=198440
The SDK takes the form of an assembly that you can simply add a reference to in your project and start using straight away. You can add the reference in Expression Blend 4 or in Visual Studio 2010, and the assembly lives here: C:\Program Files (x86)\Microsoft Advertising SDK for Windows Phone 7\Microsoft.Advertising.Mobile.UI.dll.