There's been a lot of information around Windows Server 2008 Hyper-V this year, but one of the biggest outstanding questions regarded something called Microsoft Hyper-V Server 2008, a standalone version of the Hyper-V role in Server 2008. This week, finally, those questions have been answered.

Monday, at a Microsoft Virtualization event in Bellevue, Washington, the software giant unveiled a few interesting virtualization news tidbits. For example, the company's System Center Virtual Machine Manager 2008 product, which can manage environments running on all of Microsoft's virtualization platforms, will ship within 30 days. The company also showed off some live migration features of Windows Server 2008 R2, due next year.

The most exciting news, in my mind, however, was about Microsoft Hyper-V Server 2008. To differentiate this from the version of Hyper-V that ships in Server 2008, I'll refer to the standalone version as Hyper-V Server 2008. (The Server 2008 version is called Windows Server 2008 Hyper-V.)

As with System Center Virtual Machine Manager 2008, Hyper-V Server 2008 will ship within 30 days. Microsoft had previously revealed that it would sell this product for $28, but on Monday the company announced that it would be given away for free and made available as a Web download. Like VMware's ESX solution, Hyper-V Server 2008 is a "bare metal," hypervisor-based virtualization platform. The differences between the two are interesting, and which one you'll use will depend on your needs.

First, Server 2008 Hyper-V is Microsoft's most full-featured virtualization platform. With this product, Server 2008 runs in the parent partition and provides unique capabilities around automated failover and high availability functionality. Larger enterprises will want to deploy Server 2008 Hyper-V to take advantage of that product's unlimited virtualization licensing as well.

With Hyper-V Server 2008, Microsoft's Hyper-V hypervisor is installed in the parent partition, and it provides just the bare essentials required for booting the system, providing hypervisor services, and exposing the management hooks necessary for System Center Virtual Machine Manager 2008. It does include drivers as well, but little else from Server 2008. It's not Server Core. It's much less than that: At boot time, you'll be prompted from a command line interface to configure some basic configuration options. But management occurs from the free Hyper-V management console (on Vista or Server 2008) or System Center Virtual Machine Manager 2008.

Microsoft says the performance characteristics of Server 2008 Hyper-V and Hyper-V Server 2008 are identical. But this version of the product has a few differences. It's limited to four physical processors and 32GB of RAM. There is no clustering support.

Because Hyper-V Server 2008 does not include Server 2008, customers who choose to install this version of the hypervisor will typically run Windows Server 2000 or Windows Server 2003, or SuSE Linux, in child partitions on the server. (You can run Server 2008 in a child partition, but if you're going to do that, it makes more sense to use that as the parent partition and stick with Server 2008 Hyper-V.) So it's a good solution only for those times when Server 2008 is not needed. And if you still need to run Windows NT 4.0 virtual machines, you'll have to stick with Virtual Server 2005 R2. Fortunately, all of these environments can be managed via a single tool, System Center Virtual Machine Manager 2008.

Microsoft has also opened up its certification program to its entire virtualization platform. There's a new certification specific to Hyper-V, and all of its server, desktop, and management standalone exams are being expanded with virtualization content.