Which competitors don't? The only competitor that comes to mind is Apple and they don't block this either -- though I believe they were the last holdout. Nor does Google, in any capacity, with Android or ChromeOS.
Edit: I am dead wrong. Apple only permits the virtualization of OS X on Apple hardware, per the EULA. It does not permit the virtualization of OS X on non-Apple hardware.
No you cannot. They relaxed the EULA to allow virtualization of Mac OS from a Mac OS host, however. You can also use the same licensed copy that acts as the host.
The EULA revision came along with 10.8. Prior to that you could virtualize 10.7 Server, but once again, only with Mac OS as the host, and only with another licensed copy.
And a willingness to seethe with hatred at anyone who says they resolved an issue that's plaguing you without giving any hints as to how they resolved it.
The EULA forbids you to run OS X on non-Apple hardware though.
"to install, use and run up to two (2) additional copies or instances of the Apple Software within virtual operating system environments on each Mac Computer you own or control that is already running the Apple Software, for purposes of: (a) software development; (b) testing during software development; (c) using OS X Server; or (d) personal, non-commercial use."
"They" being someone that posted an image on bittorrent? Apple doesn't license OS X for VMWare anywhere except Apple hardware. You can't even run a 10.8 guest on a 10.7 host per their license, which is really annoying.
VMWare ESXi (and Fusion too, I expect) runs legitimate installations, with no hacks required, as long as it's on Apple hardware. You need the InstallESD.img file from the OS installer.
For VMWare Fusion, not VMWare Workstation, I believe, as Workstation doesn't have an OSX version, and as others have said, their license doesn't allow for running a VM on non-Apple hardware.
It's possible to attempt using OSX on a PC through VMware, but I can attest to the fact that it works very poorly. We tried to do this at one of my jobs, and for development in Xcode, it was for all practical purposes unusable.
Edit: I am dead wrong. Apple only permits the virtualization of OS X on Apple hardware, per the EULA. It does not permit the virtualization of OS X on non-Apple hardware.
http://www.apple.com/legal/sla/docs/OSX1082.pdf