[math-fun] best published explanation of the Monty Hall Paradox?

What book or magazine article or website has the best (in your opinion) written explanation of the Monty Hall Paradox for the lay reader? (Obviously the best way to explain something mathematical to anyone is through a dialogue in which the teacher gets information from the student about the student's state of understanding and changes tactics accordingly; but I'm looking for the best canned explanation that you've seen.) Did Martin Gardner ever try his hand at explaining the paradox? Jim