XML.com: RSS Feeds for FTP Servers
http://www.xml.com/pub/a/2006/03/22/rss-feeds-for-ftp-servers.html
"this article will show you how to write a PHP script that will monitor an FTP server for you, notifying you of the newest files added or changed."
Yabfog - FTP Upstream
http://www.yabfog.com/wp/opml-editor/ftp-upstream
"The ftpUpstream script will automatically upload your OPML files as they change to the FTP server of your choice."