KnowledgeTree(tm) depends on the following components:

Email:
phpmailer - http://phpmailer.sourceforge.net (LGPL)

Mark Round's AuthLDAP class (class.AuthLDAP.php):
http://phpclasses.dknss.com/browse/package/893.html (GPL)

Javascript
MochiKit - http://www.mochikit.com/   (MIT License)
JS Calendar - http://dynarch.com/mishoo/calendar.epl (LGPL)
TinyMCE - http://sourceforge.net/projects/tinymce/ (LGPL)
Option Transfer Widget - http://www.mattkruse.com/ (Custom License)

Icons
"Silk" - http://www.famfamfam.com/lab/icons/silk/ (CC Attribution License)