This has been debated here and elsewhere many times. Do a search on "overloading polymorphism" to find threads discussing this.
My personal take on it is very liberal: since polymorphism means "many forms", then overloading is just one way of making your object/method take different forms. Of course, there are those who will argue that it isn't "true" polymorphism but hey, as long as I can do it, I really don't care what you call it
Junilu Lacar