I don’t know how many developers will be using both GoWPF and GoSilverlight for different platform targets of the same application. I know there have been a moderate number for GoWin and GoWeb.
But if you are interested in both platforms, you may be interested to know that the C# source code for GoWpfDemo and GoSilverlightDemo are exactly the same. Only the demo framework files (App, AssemblyInfo, and MainPage), not the individual samples, have significant use of #if SILVERLIGHT.
Alas, there’s no #if/#endif mechanism in XAML. The necessary differences include the XMLNS declarations, the use of go:NodeShape or go:LinkShape instead of Path, and inherent platform differences such as: