LDAP is continuing to evolve as a protocol. There are currently two working groups within the IETF to help shepherd this process:
The LDAP Duplication/Replication/Update Protocols (LDUP) working group focuses on data replication and consistency in LDAP directories. More information on the group's current activities can be found at http://ietf.org/html.charters/ldup-charter.html.
The LDAPv3 Revision (LDAPbis) working group directs its efforts toward attempting to clarify parts of the original LDAPv3 specifications. This does not include work on a Version 4 of the LDAP protocol. More information on the LDAPbis working group can be found at http://ietf.org/html.charters/ldapbis-charter.html.
While not related to standardization processes, the LDAPzone web site (http://www.ldapzone.com) does provide a nice collection of LDAP-related topics, forums, and downloads.