Cult of Mac has a story on how Scott Gilberterson crammed OS X onto an Eee PC 1000H without removing Windows XP. It turns out that the instructions for how to do this have been around for at least a few weeks at least, but I just discovered the article thanks to Boing Boing gadgets.
The only major problem with OS X on the 1000H is that the audio drivers don’t work. There’s no sound output. So if that’s a deal-breaker for you, you might want to find a different netbook to hack. Or spend the cash and buy a real MacBook.