There appears to me a new virtualization option in town, and it's free!https://itunes.apple.com/us/app/paralle ... 4709?mt=12
Parallels Desktop Lite has the ability to virtualize OS X on OS X -- or Linux on OS X -- for free. Windows is a paid upgrade.
The kicker here is that there's desktop integration for OS X guests, and 10.5 server x86, 10.6 server and later OS X versions all function on it. Plus, it can import any VirtualBox and VMWare guests that are fully shut down (no snapshots).