Virtual Security
I'm glad that you're going to look at security, because it is often overlooked in the rush to virtualise; while the points that you've made about 'virtual server sprawl' highlights that there are risks, no least of which is the potential for forgotten test applications lurking unpatched and unattended in the virtual environment. Additionally, having a coherent and manageable way of managing the real and virtual environments is critical. We have the good fortune of working with Stonesoft who have developed technologies that secure real and virtual environments from a single, centralised management console, and we are very aware of how unusual their offering is.
dp