Microsoft on Tuesday announced the immediate availability of Windows Server 2012. Microsoft is billing this Windows Server version as the cornerstone of “the cloud OS,” one that can enable smart apps across organizations from a data center, whether it exists internally or externally through a partner or Windows Azure.

“The Cloud OS is a re imagined operating system that does what operating systems have always done: manage hardware and provide a platform for applications,” Microsoft President Satya Nadella writes in a post to the Official Microsoft Blog. “But it also expands to include services and technologies that have not previously been considered part of an operating system. The Cloud OS needs to bring together all the services required by end users, developers, and IT to truly reap the benefits of the Cloud.”

Nadella cites four areas of focus for Server 2012: the transformation of the data center into a single platform that scales with a business’s needs, APIs and runtimes for building modern apps, personalized services and experiences that are available from any device, and the formalization of data as a first-class citizen in this Cloud OS.

Looked at another way, Server 2012 is arguably the first version of Microsoft’s flagship server OS that was informed and influenced by learnings from Windows Azure, Microsoft’s distributed public cloud computing platform. With Server 2012, customers can create their own private clouds, or access partners’ hosted clouds, and benefit from years of scalability work that first went into Azure.

Of course, you’re probably just curious about how you can get it. Server 2012 Standard, Datacenter, and Foundation are available with new server bundles, of course, and you can purchase versions of Standard or Datacenter normally. But TechNet and MSDN subscribers now have access to the bits as well. The fourth Server member, Windows Server 2012 Essentials, is currently available in Release Candidate form, and will ship by the end of the year, Microsoft says. And there’s a standalone (and free) Microsoft Hyper-V Server 2012, as well as an evaluation version of Windows Server 2012 that’s available from TechNet.

For more information about Server 2012, you can check out Microsoft’s on-demand launch experience and Michael Otey’s in-depth "Introducing Windows Server 2012." And Sean Deuby and I will be hosting a Twitter-based chat about Windows Server 2012 on Wednesday, September 5, at 3:00 p.m. ET/12:00 p.m. PT.