Picking up on this thread since I have kind of the same problem.
I looked at the example, which was very good, but the difference in my case is that instead of having all the xaml-code in 1 MainWindow, I have 2 User Controls put in the MainWindow. Using the example you supplied, that would mean that the RadGridView would be in the first UserControl, and the ListView would be in the second one.
If we look at my case, in both of my user controls I have a RadGridView in each, and when I select a row in the first one, the second one should get the id from the selected row in the first one, and use that for a database call to get the data that should be displayed in the second UserControl/RadGridView.
I tried to use your example with a SelectedItemsBindingBehavior class, but I just can't get it to work.
Any help is appreciated.