OnCollisionExit is called when this collider/rigidbody has stopped touching another rigidbody/collider.

In contrast to OnTriggerExit, OnCollisionExit is passed the Collision class and not a Collider. The Collision class contains information about contact points, impact velocity etc. If you don't use collisionInfo in the function, leave out the collisionInfo parameter as this avoids unneccessary calculations. Note that collision events are only sent if one of the colliders also has a non-kinematic rigid body attached.

	function OnCollisionExit(collisionInfo : Collision) {
		print("No longer in contact with " + collisionInfo.transform.name);
	}

using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void OnCollisionExit(Collision collisionInfo) {
        print("No longer in contact with " + collisionInfo.transform.name);
    }
}

import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def OnCollisionExit(collisionInfo as Collision) as void:
		print(('No longer in contact with ' + collisionInfo.transform.name))

OnCollisionExit can be a co-routine, simply use the yield statement in the function.