I cancelled my afternoon flight (PHL-IAH) and rebooked a 5:38am one which left without a hitch, though I am surprised at how "closed" the Philadelphia airport was at 4am. We did not even get a functional security line until nearly 4:40am, a mere 20 minutes before we boarded. By that time the security line was all the way to the parking garage door.

I can't really tell if any flights were cancelled, but according to the CO screens this morning at IAH, incoming flights from PHL were at least delayed a few hours.

Everyone would have loved to have seen at least one shop open so they could grab a drink or something, but the entire place was down for the count.