So far I have found two examples of a stand alone strategy for Silverlight.
Both pretty much use the same method by employing MSHTA with an *.hta file.(also achieving full trust for the application)
The trouble is these solutions are not a cross platform answer, and I don't see the benefit this would bring over a WPF click once app or an xbap application. At least its possible. Maybe Microsoft will find it beneficial to provide an attractive offline mode for Silverlight apps.