I might use one for myself, but if I was in business...
Okay, I'm a geek and love cool new tech. And the idea of computing in the cloud appeals to my geeky side, but on a practical level for business, I don't know if someone is going to want to trust access to millions or billions of dollars of financial data or corporate secrets to wi-fi or 3g connections to cloud storage. Plus, I'm a teacher and I do a lot of cloud applications like grades, online teaching, etc. If one of our services goes down for a day or two or is down for an upgrade, it is annoying, but unless it happens during finals week, nothing critical is compromised. And that happens on our servers about once a month for a few hours to a few days. A business or mission critical government operation can't say, "Oh we'll get back to you on our negotiations, Google is down" or "We'll take care of planning that military operation tomorrow because we can't retrieve the data we need from Dropbox.