Support told me this in Chat and it did in fact work for me. I finished it yesterday and we are running it now.
The process of the upgrade is fairly simple once you know the Upgrade link on Microsoft's site is a valid upgrade to the Preview.
But exactly how to get Windows 8 licensed in Parallels without a previous OS IS NOT well described. Not Parallels fault really as Microsoft does not make it clear that you can even do that. This is the first Windows OS that seems to be targeted only as an upgrade, at this point.
I would think lots of folks would like to be using Parallels with an entirely new OS license. Not everyone wants to give up the use of their PC to use Parallels on the Mac
If it is a bug it's a helpful one.
Last edited: Jan 10, 2013