Impressive figures (why does “multiplying it using industry standard metrics” worry me? but I guess it must be good even if not that good).

“According to VMware, for every server virtualized, customers can save about 7,000 kilowatt hours, or four tons of CO2 emissions, every year. (VMware said it got the figures by using the average electricity consumption of servers and multiplying it using industry standard metrics.) To date, approximately six million desktop computers and servers have been virtualized using VMware software. VMware says this has saved approximately 36.9 billion kilowatt hours of electricity each year - or more than the electricity used for heating and cooling the entire country of Denmark.”

http://www.vmware.com/solutions/consolidation/green/
http://www.pcworld.com/businesscenter/article/145169/vmwares_green_virtualization.html