At Rill & Decker Architects we run ArchiCAD on Mac OS X. If you work at Rill & Decker, this is your stuff. If you don't, but you work in ArchiCAD, you may find something interesting. Anybody else, I don't know.
Over there on the side is a division for 'Current Versions'. These are the versions of OS X and ArchiCAD you should be running. If you're not, then run Software Update and check the onion for ArchiCAD updaters.