I'd agree that reference counting is a form of garbage collection; It's what wikipedia says on it's page on reference counting. Maybe I was too hasty in my comment - or not very clear. I do think that benefits are to be had (as far as conveying information efficiently) when using more narrow and precise definitions.
I was also thinking "garbage collector" not "garbage collection". :P
I was also thinking "garbage collector" not "garbage collection". :P