imo, the mapping should be: PathNotFoundException -> 404 AccessDeneidException -> 403 RepositoryException -> 500 (or ev. precondition failed ?)
i would prefer RepositoryException -> 403. for the complete mapping see:
http://svn.day.com/repos/jcr-server/trunk/JCR_Webdav_Protocol.zip or http://svn.apache.org/repos/asf/incubator/jackrabbit/trunk/contrib/jcr-server/server/src/java/org/apache/jackrabbit/webdav/spi/JcrDavException.java
