This week's BriForum video is always a popular session during the show: The Excruciating Detail of the XenApp Logon Process (2008 Version).
Brian Madden and Kevin Goodman have been doing this session since BriForum 2006 in Washington, D.C., evolving it over time as new servers and platforms have been released. From the session description:
This session documents the steps of a logon to a Citrix XenApp Server from a successful credentials negotiation to the displaying of a published application. Each step of the process will be described in detail, including how virtual channels, user profiles, and user sessions are initialized. This is the session from past BriForums that produced the "Logon Chart," and we'll be releasing an updated chart to include XenApp 5 and Windows Server 2008.