Hi,
I've committed some fixes for WebDAV that will require running APM upgrade for file-storage and oacs-dav.
If you cvs update on the oacs-5-1 branch, please use APM to upgrade these packages right away and restart your server.
The upgrade installs a new service contract, dav_mkcol_type, which supports dav-based folder creation in file-storage. This worked before, but was a little buggy because it wasn't hooking into the fs:: APIs.