Microsoft runs over a 1000 Virtual Machines

Here's a great article based on an interview with Devin Murray, Microsoft's Group Manager for Utility Services who run the servers in Microsoft's Datacenters.

https://www.computerworld.com/action/article.do?command=viewArticleBasic&articleId=9020679&pageNumber=1

In the article Devin explains Microsoft's efforts to achieve "right sized" Server consolidation with includes a growing use of Virtualization.

Internally, Devin has acknowledges that the number is now more that 1200 VMs and growing.

Well worth a read.