Heh, and people still try to say that GAF is biased in favor of Sony.
My vote goes to the PSN hack as well. Honestly, it didn't affect me that negatively. I don't play online much, didn't upload any credit card info, and got free games out of it. But still, was a disaster and deserves to be #1.
#2 would be Nintendo's handling of the 3DS. I guess they saw how hyped everyone was at first and became as arrogant as possible. Thankfully, it sure came back to bite them in the ass. Had to do an $80 price drop within the 1st year, sell for a loss, and cut their own salaries! And all their faithful fans get are free versions of ancient games that they should have played 100 times (though that's probably all they deserve). Pathetic.
#3 is Skyrim PS3. Talk about not giving a damn and receiving the highest reward for it.