Like most things, there really isn't much new, just distilled ideas, perhaps with some terminology that makes it easier to describe (or more catchy). But yes, SaaS isn't new at all.
I think that point is the "cloud" should probably refer to things like virtual instances where you don't necessarily care what physical box they are on (or they could be running on a 'cloud' of distributed machines rather than relying on a single machine, though I don't know if that actually exists).