I've just begun testing this, and I can not get it to work either.
Actually, now that I look at the code, I would need it to go a step farther for our environment here. In addition to populating the Display Name field in RC from the cn= in LDAP, I would also need it to populate the email address itself, since we do multiple domains with a shared uid-space.
I guess I'll need to go back to using a virtusertable lookup for both of these. LDAP would have been much cleaner...