It can be done, but not stably. That said, doing so (at least with the GUI) is a violation of the OS X license, so the details may not be discussed here.
likely never... for Apple is mostly a hardware company, it's not like the to license their OS to other generic PC hardware.. plus the stability of mac is largely contributed by the fact that apple included all needed driver, so there isn't any hardware conflicts most of the times... however if it were to run on generic PC hardware, that'd be a problem
and plus, now people have been able to install OS on generic PC hardware, but it's very troublesome... not to mention illegal.
It can be done, but not stably. That said, doing so (at least with the GUI) is a violation of the OS X license, so the details may not be discussed here.