Apparently a man in Arkansas awoke from a 19 year coma (I don't have a link - it was mentioned as fact on Fark in a link to a photoshop contest).

This raises the question of whether they have a time limit for letting keeping people in comas alive. I mean, this guy was taking up a hospital bed for 19 years! Are people in comas on life support, or are they just there, alive but unconscious. Does their hair grow?