IT managers are sure that there is a lot of cost saving and reduced efforts if they move to cloud, but IT business decision makers are still skeptic. So there is a trend that organization are moving to private cloud before they decide to move on to the public cloud. I have already talked about clouds at Enter the clouds and Why i like clouds?, Private clouds can do resource provisioning and de-provisioning very fast and you have the control over your virtual environment.
VMWare vCloud ,The Enterprise-Ready Private Cloud says:
Transform your IT infrastructure into a private cloud—a pool of virtualized resources within a datacenter, or internal cloud, federated on-demand to external clouds—delivering IT infrastructure as an easily accessible service.
This cloud model enables IT to best align the service level agreement and the infrastructure to the needs of the business and the applications. This gives IT the cost savings seen from external clouds, with the security, compatibility and control needed for the enterprise.