Turba can be configured to provide multiple address books from multiple backends. This is done in turba/config/sources.php.
Someone's OpenLDAP/Turba howto:
http://ww2.redant.ca/consulting/ldap/turba.php dead link, see http://web.archive.org/web/20060708192705/http://ww2.redant.ca/consulting/ldap/turba.php
[Turba 2.1 and later]: For shared address books add the following to the bottom stanza of the source declaration:
'use_shares' => true,
When using the shared address book functionality, user and group permissions are managed directly by the user who owns the address book using the My Address Books interface in Turba, not by an administrator using the Administration/Permissions panel. Extended permissions (such as Maximum Number of Contacts) may still be set via the Administration/Permissions panel.
For sources not using the shared address book functionality, all permissions can be structured through the Administration/Permissions panel.
Hit the icon next to All Permissions to add the new top level permissions for Address Book (turba).
Select the key icon next to Address Book (turba) and add permissions for the Sources.
Select the key icon next to Sources and add the address book you want to establish permissions for.
Select the notepad icon to modify the permissions on the address book. In order for the groups to work you must have the DataTree tied to a valid source (SQL or hooks) or LDAP.