With the Bing Maps Apps SDK released, it's time to get started writing apps using Bing Maps platform. The first thing you need is something to map. "I wanted to do something a little more interesting than your typical "Hello World!" app, so I chose to map the locations of the planets relative to the earth. The necessary calculations are taken care of by CodePlex project AAPlus. To get started, download AAPlus code from CodePlex, and compile it against Silverlight runtime, or use DLL included in the attached source project. After you've that ready, you should set up your solution by following the steps in this post. Now that you're set up and ready to go, let's get to coding! We'll start by making a class that extends Microsoft.Maps.Plugins.Plugin. Plugin class is used to import and export functionality needed, and it also acts as entry point for your app. We'll need to use several contracts provided by SDK. To get a reference to those contracts, simple create public properties on your plugin class, and decorate them with an ImportSingleAttribute, and name of the contact to import," writes Ben Lemmon.
More Info: Writing Your First Bing Map App