Parallels has announced a new version of Parallels Server for Mac called the Mac Bare Metal Edition. It's optimized to provide better performance for virtual machines running on an Xserve, and allows multiple, isolated virtual machines to run simultaneously on the same server. Using "hypervisor" server virtualization, system administrators can run, say, Snow Leopard Server, Windows 7 and Linux all at once.
In case you're curious, a hypervisor is a virtual machine monitor which directly controls the hardware ("bare metal") of the host machine without using device drivers from another ope...