Apple has relaxed the licensing of its server software and will now allow users to run it in virtual machines, a sign that the company may focus more attention on the business market, said one of the companies developing virtualization software for the Mac.

The change in Apple's EULA (end-user licensing agreement) for Mac OS X Server 10.5 Leopard, first noticed by a system engineer at the University of Wisconsin-Madison, permits OS X Server to run in a VM (virtual machine) as long as each VM is stocked with a different license and the physical system is Apple-made. The new rules don't apply to the client edition of Apple's operating system, which is still barred from being virtualized.

"You may also install and use other copies of Mac OS X Server Software on the same Apple-labeled computer, provided that you acquire an individual and valid license from Apple for each of these other copies of Mac OS X Server Software," the new EULA reads. "You agree not to install, use or run the Apple Software on any non-Apple-labeled computer, or to enable others to do so."

"This is the first time they've changed their EULA to allow virtualization," said Ben Rudolph, the director of communications at Parallels, maker of Parallels Desktop for Mac. "We've known for a long time that it was technically feasible to implement OS X in a VM." But Parallels -- like its rival in the Mac virtualization market, VMware -- was leery of entering the market without a green light from Apple.

This is that green light, said Rudolph.

"Will it take some time? Yes. Are we working closely with Apple on it? Absolutely," he said. A beta, which will be publicly available but will require registration at the Parallels Web site, will be released "sometime in the next month or two," he noted.

Pat Lee, a VMware senior product manager, wouldn't commit to any timetable for his company's support of Mac OS X Server virtualization but said he too was thrilled about the change. "I'm really excited about this," he said Thursday. "There are lots of things to think about, but I can't comment at the moment on future products."

Apple, which didn't announce the EULA change or respond to a request for comment, has traditionally been a tougher sell in the business market, particularly among large organizations. But the virtualization of Mac OS X Server, said Rudolph, is a sign that the vendor is refocusing its efforts.