If you are looking for a shortcut to integrating Virtual Earth 3D into your WPF and Microsoft Surface applications, InfoStrat has released an open-source control called “InfoStrat.VE” via CodePlex under LGPL, comes in two versions: one for regular WPF applications and one with Microsoft Surface enhancements (multitouch pan and zoom gestures).
InfoStrat.VE uses some magic to eliminate these restrictions. It also takes advantage of WPF data binding for controlling various properties such as the camera location. You can add pushpins by simply adding a WPF-based VEPushPin as a child element. VEPushPins can also be provided by a data-bound collection.