Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
AFAIK, no they do not.

Usually you don't need one with an optical drive, depending on the surface.
 
If it's a smooth surface, chances are you won't need one.

However you can always buy one to make your mouse feel a little smoother.

The iMacs don't include Mouse pads =(
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.