Fellow Developers,
I posted another article in my WPF Sample Series, WPF Sample Series - WPF MVC TabControl MDI and CommandBindings.
This Sample comes with source code, a great example of using RoutedCommands to decouple the commands from the UI and where and how the command.
For grins it even has a Silverlight video too!
http://karlshifflett.wordpress.com/2008/02/24/wpf-sample-series-wpf-mvc-tabcontrol-mdi-and-commandbindings/