It only took them a year longer than it should have, but Microsoft has finally relented and approved the use of Windows Vista Basic and Premium Edition in virtualized environments, for both "consumers" and business users. Among other things, the change means that Mac and Linux users can now run Windows Vista in a VM without having to pay for the more expensive Business or Ultimate editions. This is a boon to anyone who needs virtualized environments for testing and development.

"For consumers, Windows Vista Home Basic and Windows Vista Home Premium are now licensed for use in a virtual machine environment," the company said in a statement. An updated end-user license agreement will be posted later at this location.

The move isn't a total surprise, even if it is months late. The company came very close to repealing its ban last summer, only to inexplicably pull the plug at the last minute. On the record, Microsoft said that the ban stemmed from their view that virtualization "is not yet mature enough from a security perspective for broad consumer adoption." To be frank, we never bought this excuse, because you could get the "maturity" needed to virtualize Vista for the $60+ premium that Business costs over and against Home Premium.

That debate is history now. The announcement kicks off Microsoft's Virtualization Deployment Summit, which begins in earnest tomorrow. The company is also expected to tout several other developments for business virtualization over the two-day summit, including the acquisition of Calista Technologies and an expanded partnership with Citrix.

Microsoft is beating the virtualization drum hard, gearing up for what will likely be a protracted war with the perceived industry leader, VMWare. Microsoft's message is going to be ease-of-use and cost. Bob Muglia, senior vice president of the Server and Tools Business at Microsoft, said in a statement that Microsoft estimates that "less than 5 percent of companies are utilizing virtualization technology because it is simply too cost-prohibitive and complex." Microsoft argues that it has the most "economical" approach to virtualization from desktop to datacenter, and lowering the cost barrier on the client certainly helps. Still, while great news for users who want to virtualize Vista legally, and on the cheap, it's still an open question when businesses will begin migrating to Vista in force, and if any of that migration will feature significant virtualization on the client end.

Cupertino, please start your copiers, please?!

Anytime I write about Microsoft and virtualization, someone e-mails me to remind me that Apple doesn't allow the virtualization of its client OS, which would seem to make Microsoft a "thought leader" according to some of you. Others wonder if/when Cupertino would ever allow it.

It's true that Apple doesn't allow client virtualization, and I think I speak for just about everyone when I say that no one believes it's likely to happen soon. Apple doesn't even allow its customers the legal right to run its client OS on non-Apple computers, so virtualization is out of the question.

Apple, unlike Microsoft, is in the PC-selling business, and unlike Microsoft, Apple uses a set of technological access controls to prevent its OS from running on unauthorized hardware. Why? Apple doesn't want you, me, and every other reader of this site to do what they know we'd do: run out and build our own "Macs." If you want OS X, Apple wants you to buy a Mac, period. With the company's notorious focus on control and design, we don't see this changing any time soon.