We are currently looking at adding phone book importer however at this point we don't have any plans for LDAP.
Have said that I believe that there are some products available which will expose LDAP via a JDBC interface (e.g.
http://www.openldap.org/software/repo.html).
If you can get a JDBC interface for your LDAP server than you can simply change the database connection string and each of the database queries to match your LDAP server.
Noojee Receptionist was specifically designed to work with different JDBC drivers.