Microsoft has finished most of the major work on its Hyper-V virtualization technology and expects it will be available for Windows Server 2008 on schedule in August, the company said Wednesday.

A feature-complete release candidate of Windows Server 2008 Hyper-V is now available online. Hyper-V is Microsoft's long-promised hypervisor technology for Windows Server 2008, formerly code-named Viridian.

The ability to use virtual machine technology to run multiple operating systems on a physical server, is widely seen as a disruptive technology and is becoming increasingly important as companies seek to cut costs and consolidate hardware in their data centers and IT environments. Microsoft had originally intended to release Hyper-V as part of the original release of Windows Server 2008, but the technology was delayed until six months after the server's release last month because Microsoft opted to pull out some originally planned features.

Microsoft has added support for more guest OSes in the release candidate, which now has the ability to host Windows Server 2003 Service Pack (SP) 2, Novell SUSE Linux Enterprise Server 10 SP1, Windows Vista SP1 and Windows XP SP3. Microsoft also has expanded host server support to include the 64-bit versions of Windows Server 2008 Standard, Enterprise and Datacenter editions.

Support for 64-bit OSes is critical for Hyper-V, as customers and partners think its availability for Windows Server 2008 will be a factor in moving from 32-bit versions of Windows to 64-bit versions. Microsoft is urging customers to move off of 32-bit Windows and has even made some of its software, such as Exchange Server 2007, available in 64-bit only versions, a trend that is expected to continue.

Now that Hyper-V's release is imminent, third parties also are coming out in support of the technology. A product from a company called Surgient in particular could be useful to developers that need to test applications with limited back-end server resources.

The Surgient Lab Management Platform will support Hyper-V on Windows Server 2008 once it is available, Surgient said Wednesday. The product is a virtual test environment that allows developers to test applications on a host of virtualized machines so they don't tie up live production servers.