The M button came with the Technology Package on 2008-2011 (pre .5 refresh) M3s. As of 2011.5 (production starting 9/10) the button became standard. The Technology Package was also dropped and the Competition and Convenience Packages arrived in its place.
By not having the M button, you also lose the Sport setting for Servotronic steering as well as MDM, both of which also because standard as of 2011.5 and both of which I've found to be absolutely essential for spirited driving -- Sport Servotronic restores that heavy steering feel that I want when driving hard (I prefer the standard steering for cruising around town but it's just not nearly as fun as Sport for carving up roads), and MDM lets you have some fun while not letting you get into real trouble. Not having the M button also of course means you can't program two different personalities that can be called up at the push of one button rather than messing with the other settings individually.
Last edited by jphughan; 09-03-2011 at 10:16 AM.