Below is a URL pointing to a Gartner blurb on what may next in processors: http://techupdate.zdnet.com/techupdate/stories/main/0,14179,2898075,00.html
It talks about the the number of CPUs going above 16 and the use of multiple MCMs to help z/OS. I know that z/VM supports 64 virtual machines but I have forgotten or never known how many real CPUs z/VM will support (16,32,64)?