Actually most of our components are MVVM friendly and we are always trying to improve our demos. You can take as an example RadGridView demos, or RadScheduleView demos, RadTreeView demos etc.
As for RadDiagram, it is MVVM friendly two. You can bind its GraphSource property to ObservableGraphSourceBase and this will enable two-way databinding scenarios. Furthermore, since MVVM refers not only to binding a source collection, RadDiagram provides also:
You can elaborate more on your specific MVVM scenario and we will be glad to assist you configure your RadControls.
the Telerik team