What is virtualization, and why is it important? And what's it have to do with SOA?
Way back, I talked about The Future of Computing: Pervasive, Autonomic, and Grid. (Unfortunately, IBM's "The Future of Computing" page seems to have disappeared.) One of the technological abilities that is even more fundamental than these is virtualization, which enables capabilities to be distributed across a grid, their capacity adjusted autonomically, and to be accessed pervasively from any device anywhere.
But what is virtualization? Here's a good article with that answer: "Virtualization in a nutshell: A pattern point of view." It's in the developerWorks Grid Computing zone.
Also, here's an article showing the parallels between SOA and virtualization, and how virtualization helps simplify SOA: "Virtualization as a foundation for SOA environments."