After installing the latest Mac OS X Leopard security update, namely Security Update 2008-002, my Apache stopped working. Apache's error log showed the reason why:

PHP Warning: [eAccelerator] This build of "eAccelerator" was compiled for PHP version 5.2.4. Rebuild it for your PHP version (5.2.5) or download precompiled binaries.\n in Unknown on line 0
PHP Fatal error: Unable to start eAccelerator module in Unknown on line 0

Alright, the eAccelerator extension I use to speed up PHP needs to be recompiled, because the security update has upgraded PHP (from 5.2.4 to 5.2.5). Should be easy, I thought.

A few commands later I had recompiled eAccelerator and restarted Apache by toggling the Web Server option in the Sharing preference pane, and... I got the same error. So, not so easy.