Since parallels 7 and also with 8, it is possible to use 10.7 and 10.8 (Desktop not Server) in a virtual machine.
It is supported by parallels and works fine on a real mac.

When I try to open an existing virtual machine or create a new with 10.7 or 10.8 as guest on my Hackinstosh, I get the following message:

The virtual machine can not be started. Virtual machines with Mac OS can only run on computers with Mac OS 10.5.1 or 10.4.11 or higher.

On my Hackintosh is 10.8.2 installed and it works fine with VM´s of XP or Win 7. Also the VM with Mac OS 10.7 or 10.8 works fine on a real Mac but not on the Hackintosh.

Any idea why???

Config:
Gigabyte GA-Z77-DS3H
Sapphire Radeon HD 6670 1024MB
16GB (4x 4096MB) Corsair Vengeance Black
Samsung 830 SSD
Mac Pro 3.1