If you are wondering if there is
an MVVM-friendly way to get a DataGrid’s SelectedItems into the ViewModel, read this blog post of Laurent Bugnion and find out the answer.
The issue there is as old as the DataGrid (that’s not very old but still): SelectedItem (singular) is a DependencyProperty and can be databound to a property in the ViewModel. SelectedItems (plural) is not a DependencyProperty.
Thankfully the answer is very simple: Use EventToCommand to call a Command in the ViewModel, and pass the SelectedItems collection as parameter.