A nice explanation of the direct port binding flavors in BizTalk.

Part 1: http://blogs.msdn.com/kevin_lam/archive/2006/04/18/578572.aspx
Part 2: http://blogs.msdn.com/kevin_lam/archive/2006/04/25/583490.aspx
Part 3: http://blogs.msdn.com/kevin_lam/archive/2006/06/14/631313.aspx
Part 4: http://blogs.msdn.com/kevin_lam/archive/2006/07/07/659214.aspx
Part 5: http://blogs.msdn.com/kevin_lam/archive/2006/07/25/678547.aspx

Have fun.
-- Marc