It could seem a stupid question because in my code everything is working, but I\'ve registered a singleton this way with my Unity container _ambientContainer:
I'm assuming that the ServiceLocator type is from the CommonServiceLocator project, and that you're using the Unity adapter, in which case GetInstance invokes container.Resolve, so both lines are equivalent.
You can view the source here - http://commonservicelocator.codeplex.com/wikipage?title=Unity%20Adapter&referringTitle=Home