If you're like most people, you probably named VMware or Xen first. Many of you probably know of one or more of the following: Parallels, QEMU, KVM, Virtuozzo and OpenVZ. However, few of you probably know about VirtualBox. And chances are if you know about VirtualBox 1.502, you're already running it because it manages the trifecta of being good, free and, sort of, open source.
Sort of? Here's how it works. InnoTek, a software company in Stuttgart, Germany, has released both a proprietary and a GPLv2 open-source version of the program. The VirtualBox OSE (open-source edition) has a subset of the features of the proprietary version.