How can I virtualize Mac OS X Lion?

According to the OS X EULA you may not install OS X on any hardware that is not apple branded.

(iii) to install, use and run up to two (2) additional copies or instances of the Apple Software within virtual operating system environments on each Mac Computer you own or control that is already running the Apple Software.

You do have license to install it as a virtual operating system, but only if it is run on Apple hardware.