With "INTERNAL AUTHENTICATE" command implemented, Gnuk now can be used for the authentication for OpenSSH.
We need gnupg-agent, gpgsm, and monkeysphere. If you are Debian users, just do:
# apt-get install gnupg-agent gpgsm monkeysphere
You can put the output of following command to your .ssh/authorized_keys of remote host.
$ gpgkey2ssh <YOUR-SUBKEY-ID>
For detail, please read Use OpenPGP Keys for OpenSSH, how to use gpg with ssh to use Gnuk Token for OpenSSH authentication.