A rash of hypervisor virtualization announcements last week from Microsoft, Oracle and Sun signal the game is on to beat down leader VMware and jump in the corporate virtualization revolution.

Last week's moves, observers say, expose a strategy against VMware to commoditize hypervisor technology and then win the hearts of corporate users by providing choices for management and other tools to administer what experts say is a coming explosion in virtualization on corporate networks.

VMware, which disputes any notion that hypervisor will become a commodity, has been the undisputed leader in virtualization since shipping its first product six years ago. No one is questioning the depth of its hypervisor, which eschews the stripped-down route and builds in proprietary management technology, nor are experts claiming VMware's dominance is in dispute in the near term.

Clearly, however, the level of competition and the number of competitors in the market reached a crescendo last week following August's US$500 million acquisition by Citrix of XenSource and its virtualization technology.

The long-term benefit of the coming vendor battles will be felt in IT in the form of server hardware that ships with hypervisor technology embedded and the availability of a single set of tools that simultaneously manages virtualized environments, such as servers and storage, along with physical resources.

The focus last week, however, was mostly aimed at hypervisor technology, a base technology layer that acts as the foundation for guest operating systems.

The two choices today are VMware and Xen-based hypervisors -- including derivatives from XenSource, Oracle Red Hat and Novell.

Xen is an open source hypervisor project, while VMware has a robust hypervisor that anchors its ESX-based Virtualization Infrastructure that includes management features like VMotion for disaster recovery.

Microsoft late in 2008 will add a third hypervisor option with the Hyper-V Server it unveiled last week and the Hyper-V technology it plans to add to Windows Server 2008. Red Hat and Novell also offer hypervisors as part of the operating system.

Also next year, SWSoft, which has long ignored the hypervisor model, will offer one as part of its server virtualization software, Parallels Server.

VMware reacted last week by releasing a beta of the 2.0 version of its free VMware Server.

"Everybody wants to be in the hypervisor game at some level," says Gordon Haff, an analyst with Illuminata. "There will be a choice of doing hypervisor in the operating system or on the server hardware, and that raises several big questions. Where is the hypervisor typically going to sit? Is VMware going to continue to dominate as a hypervisor supplier? And, to what degree does it end up mattering to anyone other than the vendors involved?"

It is that last question that VMware's competitors are focusing on. The idea is that the hypervisor will eventually become what hardware OEMs install on the bare metal of their servers without the need for a separate operating system. The idea is that users can plug in the hardware and instantly start loading up guest operating systems to create virtual machines.

But VMware's competitors feel base-bones hypervisors, limited to features such as live migration, high availability and centralized management, will be good enough and that corporate decisions will be made on management tools that encompass both virtual and physical environments.

Efforts to de-emphasize the robust hypervisor model are already under way.