Having just gone through evaluating various cloud providers for our high-traffic website, this is my personal definition: utility computing as electricity, meaning unlimited (in both directions) metered access. Most "cloud" companies offer neither: a typical VPS provider requires a contract that stipulates exactly how much you may consume, and when your consumption changes, you pay and wait. Imagine if you had to do that at home... a $25 set up fee and 48 hours to turn on an extra light.