While complaining will seldom alter reality, ever since Apple allowed virtualizing OS X on Apple hardware, the obvious choice for doing so was Parallels, since it's a major battle to use that other free (and partially open-source) hypervisor app to do OS X on OS X (although I have yet to get Solaris to work under Parallels). Given that situation, it seems that insofar as Apple wishes to allow either paid-up developer program members or the general public access to pre-release versions, it would be useful if Apple and Parallels could reach some agreement on what information was necessary to allow virtualizing a pre-release successfully. That would have two advantages: (1) expanding the beta tester base beyond those who had a spare sufficiently current box to run it on (or a spare boot disk and were willing to have their usual environment down for alternate boot); and (2) enabling Parallels to be ready to support the actual release as a guest from day 1 (and hopefully more quickly as a host, too). So such an arrangement would benefit both Apple and Parallels, not to mention the end user, whether using Parallels more or less operationally (i.e. after public release of the new OS X version), or using it to build advance familiarity with the new release, update their apps for the new release, etc. Even if complaining solves nothing, the frustration that something obvious apparently hasn't happened is IMO understandable.