Although WordPress / MU use its own WP authentication methods, I would state that LDAP will never be a plugin module for BuddyPress.
BuddyPress is a plugin for Social Networking – asking it to deal with authentication is like wanting your office document application to play mp3’s.
Authentication however – within WordPress / MU is pluggable and if there is a plugin out there that supports LDAP, then give it a go as BuddyPress will only check if you are logged in or out and has nothing to do with authentication.
So then if I did an LDAP module to handle authentication, would I add it to the mu-plugin directory to make it available for ALL users of the blog?
I am assuming that when a User creates their own blog, the buddy press plugins create them as an admin for that blog?
