One of our faculty reported a problem with an assignment whose availability cut-off was set for 11:55 PM Eastern Time on Saturday, March 8, 2014. This is two hours and five minutes before the expected switch to Daylight Savings Time. Students reported and he verified that access was cut off one hour earlier than expected. We manually reviewed the course logs afterwards and verified that the log times jumped from 8:59 PM to 10:00 PM, which is consistent with the DST change happening at 2:00 AM GMT.
On all our servers the timezone is set to America/New_York and this setting is forced. The actual value in the database for all our users is 99. We have America/New_York set in our php.ini and our timezone file was up to date. The server itself (RHEL6) moved to DST at the expected time and Apache logs show the expected timestamps.