Version 3.1 of Sun's VirtualBox hosted virtualization software gains new features such as Teleportation, snapshots, and 2D acceleration Sun is continuing to push its virtualization agenda forward.
If you need to use virtual machines on Linux, try Virt-Manager. Virt-Manager is more reliable than VirtualBox. Virt-Manager is completely free and open-source. I'm a long-time supporter of VirtualBox.