I made a WebDAV extension for the file manager.
It uses HTTP_WebDAV_Server php class and Moodle authentication.
With this extension, teachers are able to manage their course's folders with webdav.
For example :
http://uni.ch/moodle/files/index.php?id=473
http://home/moodle/webdav/file.php/473/
If someone is interested, a zip file is included with a readme for instructions.
I tested it only with a unix server and few windows clients (dreamweaver MX, DAV Explorer, windows explorer).
I am not very sure about security and I would be very happy if you can help me in this field
Any comments welcome !