samba - Dec 2008 - Mounting a cifs share using kerberos for authentication.

Good afternoon,

I would like to mount a cifs share using kerberos for authentication.  I'm 
able to connect to the share using smbclient:

$ smbclient //server/share -k

and I'm able to mount the share using username/password pair entered 
interactively:

# mount -t cifs //server/share /mnt -o user=smbuser

or using a `credentials' file:

# mount -t cifs //server/share /mnt -o credentials=/home/smbuser/.smbpw

After reading the mount.cifs manpage, I was led to believe that I could get 
authentication with kerberos to work using the options:

guest:  to suppress password prompting
sec=krb5:  to use Kerberos v5 for authentication

But, the following command:
# mount -t cifs //server/share /mnt -o guest,sec=krb5

failed with:
> mount error 95 = Operation not supported
I've gone through the related manpages and samba documentation to no avail.
Does anyone have any useful suggestions?

Until next time, Colin.