Robert X. Cringely thinks that Apple will offer virtualization in Mac OS 10.5, but in order to do that, he thinks Apple will need to drop Mach. "So Apple will at least offer the option for users to run a virtualized version of Windows Vista atop OS X. Don't be surprised, either, to see that OS X 10.5 has a new kernel, finally giving up Mach and a big piece of its NeXTstep heritage. I write this for one thing - because OS X has kernel problems and needs some help, especially with swap space. I say it also because of the departure of Avie Tevanian, Apple's chief software technology officer, and the guy who hung onto Mach for so long." The Mach kernel has recently been the target for complaints; esp. in server duties, OSX' kernel lags behind significantly compared to i.e. Linux.