"At the hypervisor and basic administration level, Microsoft has closed most of its technology gaps with market leader VMware (which tends to have an advantage with higher-level management and automation tools). The most significant hypervisor difference continues to be Microsoft's reliance on a parent operating system on each virtualization host -- which carries the benefit of a proven driver architecture, but the burden of potentially more planned downtime for patching and maintenance."

Citrix, meanwhile, has used its desktop virtualization expertise "to grow its foothold in the server virtualization market as the third-place vendor in terms of market share," Gartner says. But Citrix has struggled to convert users of the free version of XenServer to the fee-based edition, and Citrix's tight virtualization partnership with Microsoft presents a confusing picture to customers and partners.

Even though Gartner says VMware "continues to set the standard in the x86 server virtualization infrastructure market," and is strong in the cloud infrastructure service provider market, any gain for Hyper-V is potentially a blow for VMware. Microsoft and VMware have at the annual VMworld conference, and Gartner's endorsement gives Microsoft more fuel to add to the fire.

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in Network World's Data Center section.