Apple has long been opposed, at some level, to virtualizing its flagship OS, but a change in Lion’s EULA hints at a shift in their view on the topic.
MacRumors has reported that adopters of the new OS will be permitted to run two virtual copies of OS X on each physical machine running 10.7.
Versions of OS X before 10.6 weren’t permitted to run any virtualized copies. The restrictions were slightly lifted with Leopard, when Apple allowed users to run virtual copies provided the base OS was Mac OS X Server, and that the machine was actually a Mac, as opposed to a “hackintosh.”
It’s likely that this is simply a policy change, and users will need to make use of existing third party solutions like VMWare and Parallels.
Developers stand to benefit the most from the new rules, as virtualization is often used to test new software with quick disposable machines that don’t affect the user’s actual environment.