I have managed to make LDAP search work by doing the following, only for intranet use. I still can't make it work over the internet. I am still working on it now.
Server : name of your ldap server (only the name or ip address, ldap. or domain name should NOT be specified)
User name : uid=user name, ou=container, dc=domain name,dc=com (continue if you have .au or other extensions)
When you click on save, click on ok for non SSL and continue with save settings.
You should be able to see under the search settings your domain name appearing automatically.
Give a restart to your device and check LDAP search in contacts, email. It should work.
Please let me know if you get through with LDAP search this way.
Only thing i have changed here from earlier settings is the username format. I used to key in user name as domainname\user name earlier.
Apple has still not got back with a solution.