VMware is not a company normally associated with OSes, but it was the virtualization giant that caused a stir early last week with the announcement of its Virtual Datacenter OS, or VDC-OS. This, says VMware, transforms the data center into "an 'internal cloud' — an elastic, shared, self-managing and self-healing utility that can federate with external clouds of computing capacity freeing IT from the constraints of static hardware-mapped applications."

Perhaps getting carried away with its own hubris, the company continues: "Just like the single server OS was an indispensable part of the traditional IT stack, the Virtual Datacenter OS is an indispensable platform for business computing of the future."

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This is a little rich for two reasons. Firstly, this VDC-OS isn't out yet, so it's hard to see how it can already be indispensable. But secondly, and perhaps more to the point, it isn't an OS at all.

When it comes down to it, VDC-OS is really an expansion of VMware's Infrastructure suite with the addition of a number of modules, including:

• vCloud, which facilitates cloud computing
• vStorage, which addresses the huge storage needs that virtualized infrastructures demand with thin provisioning and "linked clones" that can share OS images to save space
• vNetwork, which feature a Network vMotion and Distributed Switch to make virtual machine networking simpler
• vCenter, an enhanced Virtual Center with automated performance monitoring and remediation for applications and physical servers, plus automated orchestration and capacity planning tools. There's also a chargeback tool that paves the way for simpler utility "pay for what you use" computing services.

vCloud is the component that has attracted most of the attention. It promises to make it simple to transfer applications between compute resources in a company's internal cloud, or to and between external providers offering services in the cloud. The company promises that "the applications that run in your business today will work the same in the cloud, without recoding or building them on a cloud-only platform." VMware has lined up "hundreds" of hosting and cloud computing service providers offering a common VMware platform, and more than 1,000 applications have been validated so they can be offered in the cloud or run in-house — and be transferred between the two — without modification.

Calling the suite an OS can be seen as a direct challenge to Microsoft: When apps are mobile and can be run wherever and on whatever it makes most economic sense to do so, server OSes and hypervisors appear less important — they become just part of the infrastructure provided in the cloud. "In your face, Server 2008 and Hyper-V!" is what VMware appears to be saying.

Chrome

Another OS that's appeared recently is Google's Chrome. Like VDC-OS it's not an OS at all — it's just a Web browser really. The link is that Google, which would love to undermine Microsoft's lucrative OS business, also sees the cloud as the future of computing. A Web browser is the key tool that many people use to access applications in the cloud, and it makes no sense for Google to rely on Microsoft to provide that tool in the shape of Internet Explorer — a part (supposedly, anyway) of the OSes that Google is trying to undermine. It makes much more sense for Google to ensure there is a browser optimized for Web applications and cloud computing (whatever that means) by taking matters into its own hands and producing its own.

Why should Chrome be seen as an OS? Holding Shift and Escape while viewing any page in Chrome brings up the Chrome task manager, enabling users to end processes within the browser. That's interesting because ending processes is a task an OS normally performs. This and other facts have led many pundits to proclaim Chrome is (or will become) an OS for Web apps. Those who don't want to stretch it that far have suggested Chrome is more of a cloud operating environment for conventional OSes, in the way early Windows releases were graphical operating environments for DOS.

What does Google say? "No, I would not call Chrome the operating system of Web apps. I think it is a very fast engine to run Web apps," Sergey Brin, Google co-founder & president, reportedly opined at the Chrome launch demo.

And who would argue with Sergey? If it looks like a duck and quacks like a duck, then it probably is a duck, as they say. But a duck that, like VDC-OS, is a challenge to Microsoft nonetheless.

"In your face, Microsoft Vista!", Brin is probably muttering.

By the time this appears, Google should have launched one genuine OS in the shape of its open source Android OS for mobile devices. If successful, Android will be powering plenty of phones in the future, and many of these will doubtless access services like Gmail, Google Calendar and Google Maps, which Google offers from the cloud. That puts Android toe to toe with Microsoft and Apple, both of which aim to offer business users access to their e-mail, calendars and other information stored remotely — either in corporate data centers or in the cloud.

"In your face Windows Mobile and iPhone," in other words.

When it comes to pure one-upmanship though, Google is the clear winner following the launch earlier this month of a satellite (on a Google-branded rocket, no less). The company has exclusive access to the digital imagery it produces for mapping purposes. As well as screaming "In Your Face, Microsoft Virtual Earth," this shows that Google has already gone well beyond the cloud — 423 miles to be exact.

Paul Rubens is an IT consultant and journalist based in Marlow on Thames, England. He has been programming, tinkering and generally sitting in front of computer screens since his first encounter with a DEC PDP-11 in 1979.