Just an FYI you definitely will see it in PHP5 as our store is based on PHP 5.2.8 and MYSQL 5.0.45. PHP5 is not immuned to this problem.
Thanks for posting this; I had just assumed it was a PHP4/PHP5 thing. I'm not sure how this behavior is controlled, but I just get a warning on divide by 0 in my configuration (whereas you get a fatal error).