Hi,
 
There is a patch in another mail that implements a "noshare" option for 
filesystems.
This allows filesystems to declare that they do not want to be exported.
The code in kern/vfs_syscalls.c:sys_mount() is there for compatability reasons.
 
Example,
 
arkanian# mount -o noshare /dev/wd0e /mnt/1
Oct 24 17:10:04 arkanian mountd[695]: "/mnt/1 -network 192.168.0.0 -mask
+255.255.255.0", line 2: Can't change attributes for /mnt/1 to 192.168.0.0:
+Operation not permitted
 
arkanian# mount | grep wd0e
/dev/wd0e on /mnt/1 type ntfs (noshare, local)

Thanks,
Matt