With unusually little fanfare, Autodesk Mudbox 2009 is now shipping for the Mac.    It looks like there will be 30-day demo version available next week.  Read about here: http://area.autodesk.com/index.php/forums/viewthread/25575/.   Not suprisingly, Pixologic (makers of Zbrush) erradicated the thread on their forums written by concerned Mac users about the lack of displacement map generation.   ZB 3.5 is still lost in space, so mac users might want to join the Mudbox party at DashDotSlash.Net, where you can find lots of tutorial material from Wayne Robson (former ZB guru) on the new sculpting entry on the Mac, Mudbox: http://www.dashdotslash.net/.