http://serverfault.com – I've been migrating some servers and desktops using Ubuntu 10.04 from getting the users from an old OpenLDAP implementation to a newer Centos Active Directory. I haven't had any problems so far, until I reached a Debian Lenny server. I've set up the server as the others, setting /etc/ldap.conf and /etc/ldap/ldap.conf. (HowTos)