In the Public Beta, the Apache web server's configuration file lived in:
/Library/WebServer/Configuration/apache.confWith the final, Apple has (for some reason) returned to a more standard (I believe) structure. You can now find the config file here:
/etc/httpd/httpd.confSneaky devils, those Apple engineers! I tested it by changing the port assignment, and it worked, so this is indeed the active configuration file.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20010325005933673