I need to refresh myself on !PRISM! now that .NET 4 is actually here. Silverlight 4 is my primary environment now though.

If you include a ResouceDictionary into Themes/generic.xaml you will receive an exception telling you that the dictionary cannot be assigned to property ‘Source’ of object, yada, yada, yada, very informative.

Problem, solution. Thanks google.

I guess it makes sense since other assemblies cannot look at the generic.xaml and use the local URI to resolve the included xaml files.