Tested with WP 3.3.1, plugin version 126.96.36.199.1.
Your plugin worked with Open Directory after I figured out the right settings.
I am working towards centralized authentication, and making WordPress ask for credentials to Apple Open Directory was a step.
While I have managed to connect to OD (which is just LDAP), the road could have been easier if I had some tips.
I) What made it work was to add CN=users to the beginning of my base DN. I would like to ask to have this tip added to the FAQ and, if possible, to the interface configuration tip.
II) RFE: The group restriction only works for AD users. It would be better if it worked for OD/LDAP users too.
Thanks for the great plugin!