In Exchange 2007 Service Pack 1, a new feature was introduced that allowed additional redundant networks to be added to a CCR environment for the purposes of log shipping and database seeding. With specific networks dedicated to log shipping and database seeding, the remaining network is dedicated to its task of servicing client communications. Such a configuration avoids situations where the network that is servicing client communications also has to process a large number of transaction logs.
Replication Host Names are an Exchange 2007 SP1 feature that I don't think is used very often or that well known. This is a great article on setting it up from both a Windows 2003 and 2008 perspective.
Via Neil Hobson.