I managed to get OS X working under VirtualBox.
It's buggy and crashes a lot, but there's one thing I don't get:
OS X's graphics subsystem does window drop shadows, smooth transition animations and effects, and reflections (e.g. in the dock) without any GPU acceleration, all at a high framerate even when under VirtualBox.
Some graphics effects aren't present, like the 'ripple' effect on the Dashboard, of course; but most of the experience is there, like the Genie effect.
What's with that? How is it that OS X does all these pretty things without requiring a GPU, yet Aero requires a GPU and Windows is totally fugly without it?
EDIT:
In before anyone starts asking about the legality-slash-legitimacy of this. I want to talk about how it works, not about anything non-technical.
