||LDAP in Mac OS X Server|
addressbook4ldap (follow the link for addressbok2ldap) is even better. It lets you manage your online address book. It even supports ssl. In my situation I use authenticated binds to read and manage the address book in LDAP. The OS X addressbook application has two flaws when you want to use it with authenticated binds. It doesn't work over ssl (so the password you send and addresses you retrieve are sent cleartext) and it uses an old authentication method. The latter can be solved by adding a line with 'allow bind_v2' in slapd.conf.
Hear us Roar