The Terminal Services Session Broker is not a new idea in Windows Server 2008, but there have been some significant security and performance improvements over the previous version in Windows Server 2003. The Microsoft Terminal Services team has a blog post explaining some of the new improvements. In a Windows Server 2003 Terminal Services environment, "when a terminal server in a farm received a connection request, it created a temporary session to authenticate the user and load user policies. more...

Read more at: http://blogs.msterminalservices.org/conger/2008/03/16/load-balancing-and-session-broker-in-windows-server-2008-terminal-services/