ArcGIS on Mac OS X with Intel Chip
ESRI do not support this but it is possible to run ArcGIS on an Apple Mac with an Intel Chip Inside (annoying intel tv ad removed here). Seems that if there is a will there is a way...
Well done and credit to Christian Spanring
One New Intel Apple Mac
Boot Camp (Windows XP emulator for Mac OS X)
Parallels Desktop for Mac