After all this time, I still love VirtualBox, the open source hypervisor from Sun (now Oracle). I use it almost everyday on my iMac to either test something in Windows XP or see what's going on in some version of Linux. It's been almost a year since the release of VirtualBox 3 made the product a real force in desktop virtualization.
The VirtualBox gang has released version 3.1.6. You can get a list of all changes in the Changelog file. Check it out.