Yeah I've seen some old accounts just started posting again today after years of not being used .
Which ones? Maybe a list should be compiled, though what Quickseller said in another thread will also be relevant that many older inactive members will be likely to return to change their passwords by the email they received from theymos.
Yes, it is probable that old users will return to change their password just for precaution, but posting nonsense from inactive accounts for years? That should ring a bell.
This, like the Mt.gox support's account... he is trolling and post useless posts around the forum . This should alert everyone that those account(s) were hacked and it is (or better they are) under the control of the 'hacker' who has attacked the forum .