I'd like to make you aware of the SAP Compendium, which has been published by SearchDataCenter.It contains a rich set of information on "Virtualized SAP environments" on more than 70 pages. You will find information about:
Benefits and Examples of SAP virtualization
Why SAP SOA requires virtualization ?
SAP Virtualization workshop
TCO & ROI Analysis
It is available at VMware's EMEA shop.