Microsoft stuck a shiny piece of coal in VMware's Christmas stocking Thursday morning when it sent its competitive - hithertofore repeatedly delayed - hypervisor-based server virtualization technology Hyper-V out for a surprise public beta.

The Hyper-V beta wasn't supposed to come out until the first quarter. It hasn't changed final release though. It's still penciled for within six months of when Windows Server 2008 RTMs.

VMware, which had almost clawed its way back to $100 a share after half-real, half-imagined competition fears knocked it down to close to 70 bucks right after Thanksgiving, lost $3.23 to settle at $96.

Microsoft has been letting it slip that Hyper-V is three times more efficient than VMware. VMware says it doesn't know what Microsoft means by efficient but it does know that it's been delivering more functionality than the Hyper-V beta dreams about for the last year or two and that 80% of its accounts are in production.

Hyper-V is supposed to be bundled in three editions of Windows Server 2008 and Microsoft said the Windows Server 2008 RC1 Enterprise with the beta version of Hyper-V could be downloaded for customers and partners to evaluate the technology, test applications and make plans.

The beta is the English language version of x64 Enterprise Edition. Those facts alone will limit how widely the beta can be tested, according to VMware senior director of product marketing and alliances Reza Malekzadeh.

Microsoft said it had features and capabilities not available in the Community Technology Preview of Hyper-V put out in September, such as Quick Migration, high availability, server core role and server manager integration.

Malekzadeh says Microsoft's Quick Migration is a rebranding of its host clustering facility and, unlike VMware's VMotion, can't move virtual machines around without downtime.

Microsoft volunteered that it's developing the next version of System Center Virtual Machine Manager to provision and configure virtual machines, and centrally manage the virtual infrastructure, running on Hyper-V, Microsoft Virtual Server 2005 R2, VMware ESX Server and Virtual Infrastructure 3 (V13).

See http://www.microsoft.com/ws08eval.