Essentially very similar to IP Masquerading. Lots of flexibility in schedulers in choosing which server to use.
Front end is termed a director.
Backend servers termed real servers. Lead developer - Wensong Zhang. Mike Wangsmo, Rob Thomas, TC Lewis, Matthew Kellett, Mike Douglas, Horms, VA Linux, Redhat, plus a number of the usual suspects. IBM's Net Dispatcher has the service IP public on the director, and private on the real servers. The director modifies the ethernet packet's MAC addresses to that of the ereal server.