Just a bit of warning about the php5-cgi 5.3 update that is recently made available.
I am running a source install of knowledgeTree community edition and has done so for over a year with the php5-cgi contrib version 5.2.8.
Without thinking to hard I did a yum upgrade for the php5-cgi 5.3 that was available and found that my knowledgeTree installation came to its knees

For example the knowledgeTree background scheduler stars spouting these errors:
# /usr/bin/php5/php /opt/knowledgeTree/bin/scheduler.php
Deprecated: Assigning the return value of new by reference is deprecated in /opt/knowledgeTree/lib/validation/customerrorviewer.inc.php on line 44
Deprecated: Assigning the return value of new by reference is deprecated in /opt/knowledgeTree/lib/validation/customerrorhandler.php on line 44
Deprecated: Assigning the return value of new by reference is deprecated in /opt/knowledgeTree/thirdparty/pear/Config.php on line 79
Deprecated: Assigning the return value of new by reference is deprecated in /opt/knowledgeTree/thirdparty/pear/Config.php on line 165
Deprecated: Assigning the return value of new by reference is deprecated in /opt/knowledgeTree/thirdparty/pear/Config/Container.php on line 107
Warning: The magic method __get() must have public visibility and cannot be static in /opt/knowledgeTree/search2/indexing/indexerCore.inc.php on line 99
Warning: The magic method __set() must have public visibility and cannot be static in /opt/knowledgeTree/search2/indexing/indexerCore.inc.php on line 119
Warning: The magic method __get() must have public visibility and cannot be static in /opt/knowledgeTree/search2/indexing/indexerCore.inc.php on line 151
Warning: The magic method __set() must have public visibility and cannot be static in /opt/knowledgeTree/search2/indexing/indexerCore.inc.php on line 165
Deprecated: Assigning the return value of new by reference is deprecated in /opt/knowledgeTree/ktapi/ktapi.inc.php on line 752
Warning: session_start(): Cannot send session cookie - headers already sent by (output started at /opt/knowledgeTree/lib/validation/customerrorviewer.inc.php:44) in /opt/knowledgeTree/ktapi/ktapi.inc.php on line 44
File size limit exceeded
Turns out that knowledgeTree 3.7.0.2 is not (yet) supported on php 5.3. They state php 5.2.x as a system requirement.
So I removed the php5-cgi 5.3 and reinstalled the 5.2.8 version that I still had in my yum cache and all is happy again.