I had hoped to finalize a write-up of the new Windows Server 8 Beta today, but it looks like that will happen tomorrow, sorry. In the meantime, Microsoft did announce the release of the Beta and provided a bit of information. 

First, you can grab the Windows Server 8 Beta download from the TechNet evaluation center. It's a 64-bit OS only, like Windows Server 2008 R2 before it, but Microsoft has made two versions of the download available, an ISO (3.3 GB) you can burn to disc (or copy to bootable USB device) and install manually or a preconfigured VHD (virtual hard disk, 2.4 GB) for Hyper-V, Virtual PC, or other virtualization environments. Annoyingly, you have to step through a sign-up process to get either. English, Chinese, French, German, and Japanese versions are currently available.

Microsoft told me in a briefing earlier this week that users might consider the Windows Server 8 Beta to be an "IT pro preview," similar in fashion to the Consumer Preview moniker that the client team is using for Windows 8. The point being that many of the improvements you'll see in this release relate to the admin and management interfaces, especially Server Manager, which is now even more core to the experience than ever before.

"Now is the time for you, IT professionals in organizations of all sizes, to get your hands on this new release, discover the new capabilities and contribute to the development of what we call the cloud-optimized OS," Microsoft corporate vice president Bill Laing wrote in a post to the Microsoft Server Blog. "I can't wait for more people to start trying out Windows Server 8 and letting us know what they think."

Laing highlights the following key changes in the Windows Server 8 Beta:

Hyper-V. "The new Hyper-V takes virtualization above and beyond to provide a multi-tenant platform for cloud computing. For example, with Hyper-V Network Virtualization you can create virtual networks so different business units, or even multiple customers, can seamlessly share network infrastructure.  You will be able to move virtual machines and servers around without losing their network assignments."

High availability and disaster recovery. "With File Server Transparent Failover you can now more easily perform hardware or software maintenance of nodes in a File Server cluster by moving file shares between nodes with little interruption to server applications that are storing data on those file shares."

Multi-machine management and automation. This is what I consider to be the key change in Windows Server 8, thanks to the new focus on remote management and the excellent new Server Manager. "With .NET Framework 4.5 you can take advantage of new asynch language and library support to build server and web applications that scale far beyond what other platforms provide. Our new IIS 8 web server provides better security isolation and resource sand-boxing between applications, native support for web sockets, and the ability to host significantly more sites on a server."

More on Windows Server 8 soon. ASAP.