A conversation I sometimes get involved in with customers is, "How should we secure vSphere?" The environment doesn't have to be VMware-based of course, it could be Xen, Microsoft, Red Hat or any other, but the question remains.
From a technical perspective, the set of risks is reasonably well understood and by and large appropriate mitigations exist. For example each virtual machine, and the network connections between VMs need to be as secure as their physical equivalents. Meanwhile security holes could exist in the hypervisor layer, as with any other software package. Protections such as defence in depth, intrusion detection and prevention, patch management and so on remain much the same as in the traditional, physical world.
However, the net-new of a virtualised environment lies in how VMs are provisioned and managed. It is clearly much easier to deploy a virtual machine than a physical...