VirtualBox is a general-purpose full virtualizer for x86 hardware. Targeted at server, desktop and embedded use, it is now the only professional-quality virtualization solution that is also Open Source Software.
Major new features:
Guest SMP with up to 32 virtual CPUs (VT-x and AMD-V only; see chapter 220.127.116.11 of the user manual)
Windows guests: ability to use Direct3D 8/9 applications / games (experimental; see chapter 4.8 of the user manual)
Support for OpenGL 2.0 for Windows, Linux and Solaris guests
Tools and Utilities
Windows, Linux, Mac
Product page: here