Hello,
Ccheck out the following resources:
http://www.virtualizationbookshelf.org< books on virtualization and security (just use the 'security' tab)
http://www.vmware.com/security< blogs on security of the vSphere environment
http://www.virtualizationpractice.com/topics/virtualization-security/< articles on virtualization and cloud security
VASTO < metasploit plugin for virtual environment security
http://www.vmworld.com and many other conferences < check out old presentations on virtualization security
Read through this forum
There are lots of resources and places to start.
Best regards,
Edward L. Haletky