Plone WebDAV
Come up a few times on the list. The difference between using WebDAV and not is that in a WebDAV client when you get a page, you want to get the source to edit the page, not the HTML with the rendered template. To do this Plone tries to determine if you are using WebDAV or not, one way is to use port 1980, the WebDAV source port in zope.conf.
An easier way I prefer is adding your client to the zope.conf so that it recognises your client as WebDAV. This makes a simple change for Zope's sitting behind a proxy. To use finder with Plone add the following webdav-source-clients line and then restart:
<http-server> webdav-source-clients WebDAVFS address 8080 </http-server>