I am this close (fingers only an inch apart) to moving completely to OS X as my vulnerability assessment / pentesting platform. The only thing stopping me is the fact that VMWare doesn’t run on OS X (yet).
Between Fink, Darwin Ports, and eventually Portage for OS X, we have most of the *nix security tools covered. All we’ll need at that point is a decent Windows environment (most Windows security tools run on Windows) — and from what I understand VirtualPC does not fit the bill.
So, VMware, please do this for those of us who need a fast, dependable multi-OS environment from within OS X. I for one would buy it the first day it became available.