In the current (April 2012) issue of Visual Studio Magazine, I wrote an article that describes the new Bing Maps for WPF control API library. See http://visualstudiomagazine.com/Articles/2012/04/01/Map-Your-Apps.aspx. The library allows you to directly place a Bing Maps map into a WPF application. This is particularly useful when you have a large amount of geographical data in a backend database that you want to place on a map. In that scenario, using Bing Maps AJAX (i.e., in a Web page) or Bing Maps for Silverlight often don’t give you the performance you need. Additionally, you get the power of WPF (such as drawing shapes and capturing user interaction) that you can overlay onto your map. New technologies come along all the time, but Bing Maps for WPF is something that is extremely cool in my opinion.