MAC desktops (iMacs, Mac Mini, Mac Pro) don't natively support touch unless you buy a device specifically made to support for MAC. Cintiq makes pen based monitors that work with MAC, for instance, but only for specific applications.
MAC = media access control address.
Mac = the computer hardware made by Apple, Inc.
Sorry, minor pet peeve. ;)
OS X really isn't optimized for touch at present. It's designed to be a desktop/laptop OS, not a mobile device OS.
Based on using LogMeIn Ignition on my iPad to access my Mac it does work rather well however. Go to System Preferences > Dock and uncheck the Magnification option though. I've found that option made the icons in the dock very poor touch targets.