Oliver Schneider wrote:
  I think this
might be a little restrictive.
A NT filesystem doesn't have to operate solely in kernel
mode.  The kernel mode component is free to delegate work
to a usermode component if it chooses.  (In fact, if
I'm not mistaken, Microsoft's webdav filesystem driver
works this way.) 
 The WebDAV component of MS I know is completely in usermode. It is just a
 shell namespace extension. 
 
I give you pudding :-) (The proof is in the pudding right?)
Run WinOBJ and take a look at Device directory.  Notice
the \Device\WebDavRedirector device.
WebDav is a filesystem driver (of the kind refered to a
network redirector, but non-the-less a filesystem driver.)
Thanks,
Joseph