I don't get spoofing TX-ID's for the whole network. Why not do it just for yourself so you can try and duplicate your coins from an exchange instead.

Doing it network wide is obviously just an attempt at crashing the market so the attackers can buy in. Well that or it's Gox doing it as a little tantrum over the fact they got cleaned out by someone using it.

It's not a real attack and gains very little besides market manipulation, gives Gox an air of legitimacy however.