VMware has reversed course on allowing users to virtualize client installs of Mac OS X Leopard and Snow Leopard. The company made a short post on its blog late Monday acknowledging the extra client support that appeared in Fusion 4.1, but claimed the software's previous checks for the server editions of those operating systems had been left out. VMware therefore plans to issue an update that will once again restrict users to installing only Leopard Server, Snow Leopard Server, Lion, or Lion Server.

VMware Fusion 4.1 was released late last week with a handful of updates, but the most interesting (and, at first, undocumented) change was that the software apparently stopped restricting users to the server versions of Leopard (Mac OS X 10.5) and Snow Leopard (10.6). Instead, Fusion 4.1 presented users with a confirmation screen reminding them to "verify that the operating system is licensed to run in a virtual machine."

According to the VMware blog, the confirmation screen is supposed to be new in Fusion 4.1—but the ability to install client versions of Leopard and Snow Leopard is not. "When the license verification step was added in VMware Fusion 4.1 the server edition check was omitted. We are preparing an update," the company wrote. "Running Mac OS X client in a virtual machine continues to require Lion (purchased from the Mac App Store or a USB thumb drive.) Users should always ensure they remain in compliance with any applicable software license agreements."

We can't help but wonder whether VMware received a call from Apple legal over the matter, but without any further information, we'll take their word that the "feature" was unintended. The question now is: how many people will race to install one of the restricted OSes in a virtual machine before VMware issues another update?