It official: if you own a recent "decent" or new Apple PC/MAC, or thinking about getting one, you can actually buy (or side upgrade to) a version of the program designed with your Operating System in mind.
No, it's not a half-baked port of a Windows app, and no it has no Ribbon (that's a Microsoft "thing", not Apple): it's is a true Apple OS application built from the ground up. Looking for screenshots, details, trial versions and purchase information at http://www.autodesk.com/autocadformac
Are you a student (or educator) with a MAC? You too can get in on this with a FREE (yes, free) Educational Version of this application for all your College/School needs. Details and licensing restrictions are at http://www.autodesk.com/mac4students