I am not a Leafs fan, I'm your dreaded Habs fan and even I have to say that the hit was clean. May had his head down and had just barely lost the puck, Sundin was just finishing the check. I don't have the rule book in front of me, so correct me if I'm wrong, but I believe the defender has the right to finish the check so long as it wasn't roughing/charging or other infraction, and it could be seen as reasonable that the defender was already in the action of hitting the offensive player as he lost the puck. Again, that's how I saw it and interpret the rule, but I'm not an NHL ref either.