Gox has been teetering on the edge of disaster for 6 months+ since it basically stopped offering most users in the world the ability to quickly and easily cash out FIAT.
IMHO this "bug" in Gox's wallet (that presumably has been know of for a long period of time) is just an excuse.
IMHO they've gone insolvent, cashed out their no doubt ginormous profits, and left everyone else to suffer. The reason they can't pay out people's bitcoins is that they aint got no bitcoins left to cash out for people!
IMHO people have been trading bitcoins and FIAT back and fore that were already injected into GOX months ago - essentially paper trading - there's been no actual FIAT or Bitcoins in the system so now finally the poop's hit the rotational cooling device and no one can cash anything out.
I hope to be proven wrong as Gox has been a main player in the success of bitcoin - but the sheer amount of profit they must have made on every single trade means they can all cash out millionaires and leave their customers to deal with the loss.
Butuz