I had another random thought, it might be crazy, but I thought I'd share it. I think I may have been completely wrong in describing cloud computing as a metaphor or analogy, or more simply as Internet centric infrastructure.

Let me explain, the Internet is a physical network implementation. Basically the Internet can be thought of as a network of networks interconnected linked by copper wires, fiber-optic cables, wireless connections, and other physical hardware based aspects. In contrast the world wide web is a system of systems or a series of independent but interrelated elements comprising a unified whole -- the application.

To put it another way, the problem with describing cloud computing as a metaphor for the Internet is it's actually a "euphemism" for the world wide web.

According to wikipedia, Euphemisms may be formed in a number of ways. A Periphrasis or circumlocution is one of the most common — to "speak around" a given word or concept, implying it without saying it. Which it seems is what we are actually doing when referring to "cloud computing". Over time, circumlocutions become recognized as established euphemisms for particular words or ideas. Basically cloud computing is an other way to describe the web, or more broadly the next generation of the world wide web.

With this in mind, I think the challenge in trying to define a simple common definition for cloud computing is that we've been describing the wrong concept. We're not describing the physical infrastructure of the Internet so much as the application of that infrastructure.