Red Hat Linux 6.1 includes some basic LDAP integration. The packages included allow a user to setup an LDAP server, migrate other name services info to ldap, and provide all the client tools needed to authenticate via ldap.
NOTE: There is a bug in the nss_ldap package in 6.1. I recomended upgrading to the version from rawhide.
This info is pretty plain at the moment. I hope to covert it to DocBook and expand it a bit later. Most of this can be found elsewhere, so hopefully this concentrates on the Red Hat Specific bits.