One of the big difficulties of the cloud is properly defining it. I don't think it will be completely defined for a while yet. Since that is the case, I think I would like to muddy the waters a little more.
Is VOIP a cloud service? It's a service, runs on the internet, on someone else's servers, in a location that I have no clue about. Isn't that SaaS? Ok, maybe something like Vonage, Cable Phone or Verizon is really a utility. Those actually have hardware in my house.
What about Skype, MSN Messenger or Yahoo Messenger? All of those can make phone calls to others using the same service. All the things I said about the VOIP providers above apply. So, is Skype a cloud service?
Actually, let's look at Yahoo Messenger. I can make video calls, do instant messaging and more. It really is a service and it gets more functionality all the time.
These ride a fine line. What do we call a service (SaaS) versus just a regular internet application? Or, is every internet application now a service?
It's a conundrum. ;-)