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.