I’m honored to have just been published on Edgewater’s public blog…
It’s bit about managing infrastructure agility. The basic idea is architecting your infrastructure so that you can push off parts to different clouds when you need to, for any of a multitude of reasons. The idea goes a bit beyond virtualization.
Check it out:
http://edgewatertech.wordpress.com/2009/04/24/best-practice-cloud-computing/