Today I have downloaded the brand new Knoppix 5.0.1 DVD and played a bit around with it.
It looks quite nice, although some of the packages are very up to date and others are quite old. MySQL comes with 5.0.21, so there's probably no distribution with a more recent MySQL version at the moment.
PostgreSQL is included with version 8.0.4, while the current version is 8.1.4 (and the latest version of the 8.0 tree is 8.0.8). Apache comes with versions 1.3.34 and 2.0.55, but only Apache 1.3.34 is configured to start with PHP and that only with PHP 4.4.2, which is the most disappointing aspect that I found.