There is a very good article about the debate around private clouds entitled "Are Private Clouds Hogwash?" by Michael Neubarth. He quotes me, and about a dozen other people.
"Ever since the idea of a 'private cloud' was introduced, there has been a backlash against the concept, including contention about whether a private cloud is really a cloud."
My good friend Mike Kavis had some great insights into this as well on his blog.
"One of the biggest benefits to the business for cloud computing is the reduction of capital expenditures brought about by outsourcing hardware and data center costs to a third party provider. Choosing to build your own cloud on-site is like building your own refrigerator. Sure you can do it and you can have total control over it, but it is way more expensive, labor intensive, and will take you forever to get it done."
Of course with the renewed interest in this debate, I've been getting a lot of questions around my take on the use of private cloud as a way to describe this specific types of architecture. I come down somewhere in the middle.
The fact of the matter is that private clouds are a useful architecture patterns, and they are really an SOA that use some virtualization and multi-tenancy at the end of the day. Thus, while people are getting wrapped around the axle around the use of the term "cloud" to denote something that's actually not in the cloud, or the Internet. Therein is the essence of the debate, as well as the confusion.
I don't care what you call it, but I can tell you that this type of architecture is a legitimate and workable architectural pattern. The idea is to "borrow" what works in the public cloud, and leverage that for systems that can't exist in public clouds. Nothing wrong with that.
NIST uses the term, I use the term, and I suspect we'll all be using this term at some point in the future. If it works, I'm for it. I don't care what you call it.