dude what's the point??
it's old news, it doesn't work, don't be a crook.
It would work if someone delivers the non-returnable goods after 0 or 1 confirmations. It gets harder as the amount of confirmations goes up (and even with the slump so far, the Bitcoin network is still powerful enough that it's non-trivial to even do with one confirmation).
It's not that it doesn't work, it's that the payoff is probably not worth the amount of effort required to do it. No one moving a sizable amount of money is going to not wait for confirmations and the longer they choose to wait the harder the attack gets.