OS X PB ships with version 1.3.12 of the Apache web server. If you'd like to run the latest release (1.3.14), there's a good article on stepwise.com explaining how to do so.
Their instructions leave you with two Apache installs, in case you want to revert to the prior version.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20001127194811650