I actually should better ask “is a Private Cloud really Cloud Computing?”
Quite frankly i do not think that what Gartner and many others call a <Private Cloud> is anything near Cloud Computing. Agreed there is a trend towards virtualization and this makes perfect sense for large corporations – but Cloud Computing for me implies that the user (and even the IT department) does not know where the application or service is running and where data is stored.
The reason to use a Private instead of the Public Cloud is most of the times security related, i.e. I want to assure that sensitive data is not leaving the company in order to reduce risk or ensure compliancy with corporate policy or laws. Distributing the available internal computing power and the available storage across many users, apps, departments and locations is more or like a task of clever load-balancing. Some of the technology is probably similar to the one used in the Cloud, but all this is still very much in the control of corporate IT.
The fact that I am sure that the data does not leave the companies firewall shows that I always know where it actually (and physically) is. Isn’t this is an antagonism to the concept of Cloud Computing?