I noticed that after upgrading my server to 10.3 I lost FTP services. Apparently I am not alone in this problem. It seems that Jacin Ferreira on the Apple Discussion boards found a solution that I am reprinting here to aid others:
Please look in /Library/FTPServer/Configuration/Messages/ and look for a file named shutdown.txt inside that directory. If it is there, trash it and restart your FTP server.It worked great for me!
Mac OS X Hints
http://hints.macworld.com/article.php?story=2003121711300728