Can Turba use shared address books?
[Turba 2.1] Shared address books are available in current versions of Turba. Any user can create a new address book and set the appropriate permissions on it to make it shared. To enable this, make sure the ‘use_shares’ => true option is set in turba/config/sources.php. Choose the menu item My Address Books and then select the address book you want to share from the drop down menu in the Edit Address Book section then click Edit Permissions.