[MrJackdaw]

Note to developers: The save on unload facility appears to be fixed in the latest patch!

As an example;

if ( Plugins ["NameOfPlugin"] ~= nil ) then
	Plugins["NameOfPlugin"].Unload = function( sender, args )
		CallYourSaveFunction()
		Turbine.Shell.WriteLine("All data saved!")
	end
end

Now appears to work properly at last!