MacEvangelist has an interview with someone who claims to be working on a PS2 emulator for OS X:
A new startup that I was a part of created a PS2 debugger for MacOS X. It was during this consignment that we thought, "why not make a PS2 emulator?" Things has gone very well, we are seeing leaps and bounds in development and we are excited with the way things are going. We are now trying to work with Sony and Apple to release a fantastic product sometime in 2002.
Seems to be a technically challenging task... so take it with a grain of salt...