Just a quick note for those with custom apache setups. Installing the 10.2.4 update will replace your /etc/httpd/httpd.conf file with a default Apple standard which will disable any custom modifications you've made (eg. PHP won't be enabled, custom aliases won't function, et cetera). Your old file is copied/renamed to httpd.conf.applesaved.
To revert back to your apache setup, simply copy/move this file to its original name "httpd.conf." You could back up the apple created file but it's not necessary.
[robg adds: This was mentioned in the comments to this hint, but I thought it was worth mentioning on its own. I would disagree, however, that it's not worth keeping the Apple file. The Apple httdp.conf file installs the new mod_rendezvous module, which you may very well wish to keep. I just used this week's Pick of the Week, FileMerge, to compare the two httpd files and eliminate the differences.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030214134914285