I've thought that WebDAV and RDF are made for each other (especially, storing and searching metadata). The Twingle project is another one mingling the two to provide "Locating, Creating, and Collaborating" from within Mozilla. It apparently uses a true MVC pattern and the model is represented as RDF.
"Twingle reinforced the lesson that quick, tangible efforts are ideal for bringing unity." - Against the Grain: Getting Projects To Work Together