The Burton Group, an analyst firm acquired by Gartner last year, in Microsoft's Hyper-V, including its approach to disaster recovery.

Although VMware still touts more robust management software, Microsoft has steadily added features, including live migration and memory oversubscription, that Hyper-V could be used alongside VMware deployments. Even before the rise of Hyper-V, the Burton Group declared that essential virtualization and requirements and could be considered "production-ready."

But in the 2010 Magic Quadrant, Gartner faulted Microsoft for "limited innovation and reactive strategy in a rapidly evolving market," saying "Microsoft is still learning about this market and its needs, and will need to continue to improve its product strategy and technology innovation to become a leader."

In the same 2010 report, Gartner said Citrix's "product functionality [is] second only to VMware."

Things have changed. In last week's report, Gartner says: