More Information on the Virtualization of Microsoft Websites
If you read my post from the other day, you will now know that MSDN and Technet are running completely virtualized. We are talking over 4 million hits per day with 5-6% CPU utilization! You can find the details of how this works here. A very interesting thing to note: Physical CPU loads showed about 21% better performance than a virtualized CPU. This, honestly, is very acceptable. The interesting part, is that requests per second per 1% CPU performance of MSDN over the previous physical server platform improved. Meaning, they are actually getting more performance per CPU with the virtualized environment.
You can also find another great BLOG posting on the details here.