Apple appears to have relented and given its tacit support to virtualisation of Mac OS X Leopard. However, Apple’s terms continue to make virtualisation on Mac servers less attractive than they might be.

Several users have spotted a change in the End User Licence Agreement (Eula) for Leopard. Until the new terms, Apple’s official position was that Mac servers could not run multiple instances of the OS without breaking its terms and conditions.

At the first sight, that change is a boon for Mac server admins wishing to run several instances of the operating system, as well as earlier Mac operating systems, or Windows, Linux, Solaris or other third-party guest operating systems that run on Intel hardware.

Experts noted that firms wishing to run multiple instances of Leopard will need a separate licence for each, making the exercise potentially costly but virtualisation companies were nevertheless impressed.

“It’s very good,” said Serguei Beloussov, chief executive of SWsoft, which is developing Parallels Server for Mac. “We were trying to convince Apple for quite some time but they’re so super-secretive. We definitely will support it.”