Fons Sonnemans just published an improved version of his MineSweeper game which now supports right mouse click.
I have written a Silverlight Minesweepe game in October 2008. I just published an improved version on Silver Arcade which support right mouse click. I implemented it using the following RightMouseTrigger. You can set the SetHandled property to true. This stops the MouseRightButtonDown event from bubbling to it's parent.
I really love Behaviors, Actions and Triggers. I hope you like it too.