Microsoft released iPhone and iOS to Windows Phone 7 API mapping tool.With this tool, we can easily develop a Windows Phone 7 application from an application whose code in iOS/iPhone.Microsoft also released Android to Windows Phone 7 API mapping tool.
With this tool, iPhone developers can grab their apps, pick out the iOS API calls, and quickly look up the equivalent classes, methods and notification events in WP7. A developer can search a given iOS API call and find the equivalent WP7 along with C# sample codes and API documentation for both platforms.
You can also share your libraries, methods and classes in the MSDN library here.
Download the API mapping tool.