> VMware plays fiddle to apple's artificially restrictive licencing
VMware merely passes relevant host information to the guest.
For OS X this is something (can't remember) that satisfies the "Dont Steal Mac OS X" kext. For Windows and PCs with embedded license signature keys (again, can't remember the name, SLIC or something like that) then they're passing that (making virtualized Windows+Office OEM licenses activate against the original hardware†). VirtualBox does not (or did not last time I had to patch it), and it's a pain, putting you in all sorts of legal grey areas for something the license allows.
Summary: important system binaries (such as Finder.app) are encrypted with a key held in the SMC. The OS transparently decrypts them, but needs access to that key to do so.
It is possible to convince QEMU to run OS X: http://www.contrib.andrew.cmu.edu/~somlo/OSXKVM/ (though I've not tried this myself). They do require you to provide the relevant key yourself, I imagine for legal reasons.
You can also use FakeSMC, which is a kext that emulates a real SMC and therefore allows you to bypass that limitation. It's a mandatory requirement for Hackintosh installations.
VMware merely passes relevant host information to the guest.
For OS X this is something (can't remember) that satisfies the "Dont Steal Mac OS X" kext. For Windows and PCs with embedded license signature keys (again, can't remember the name, SLIC or something like that) then they're passing that (making virtualized Windows+Office OEM licenses activate against the original hardware†). VirtualBox does not (or did not last time I had to patch it), and it's a pain, putting you in all sorts of legal grey areas for something the license allows.
† also works on a hackintosh