I'm using Novell's JLDAP Java library (available from http://www.openldap.org/jldap/) to talk to my OpenLDAP server from an application developed in-house. It's been a pretty straightforward ride: I can list users, change attributes, etc. There is, however, one thing I haven't yet been able to implement - create a new user that inherits the objectClass "posixAccount". According to Novell's code samples, to create such an entry, one would do:

        LDAPEntry entry = new LDAPEntry(cn);
        LDAPAttributeSet attrSet = new LDAPAttributeSet();
        // Object class descriptions
        attrSet.add(new LDAPAttribute("objectclass", new String("inetOrgPerson")));