DailyTech has a great article, an interview with Nissan on how they are using Virtualization and why they picked Hyper-V over VMware.  There are some great details on their implementation and I think the final quote sums up what we keep saying

 "For other companies considering virtualization, but unsure of the costs and benefits, Matt Slipher suggests, "Make your own judgement.  Get your tools and test them.  We got [competitive offerings] and tested them... [For us] Hyper-V was less of a learning curve."