I saw these 2 basic ways of namespacing in JavaScript.
Using object:
var Namespace = { };
Namespace.Clas
Well, if all you're doing us using that "Namespace" thing as a way to "contain" other names, then those two approaches are pretty much exactly the same. A function instance is just an object, after all.
Now, generally one would use a function like that if the function itself were to be used as a constructor, or as a "focal point" for a library (as is the case with jQuery).