I just posted a new solution for implementing drag-drop between ListBox and other controls, and in case you are using WPF - other applications. You can find more information and a sample application here:
http://www.telerik.com/community/forums/silverlight/scheduleview/listbox-drag-drop-behavior.aspx
Best regards,
Valeri Hristov
Telerik
http://www.telerik.com/community/forums/silverlight/scheduleview/listbox-drag-drop-behavior.aspx
Best regards,
Valeri Hristov
Telerik