Kevin's story is backed up by MtGox's own feed; and that showed that he could not have made the order before the crash. In fact, 6 people got in before him when the large order finally finished executing - which took 35ish minutes.
OK, Not the hacker.
Still a dick for wanting to keep the BTC.
Kevin. Listen to me: The rollback is happening for one simple reason: It is the easiest way to make as many people as whole as possible. You will get your money back, and may end up ahead by over 600 bitcoins. I am sorry you're not a millionaire. You acted in good faith, as most of us would, to snap up as many of the coins as possible. As it turns out, those coins didn't belong to the person selling them. This means that they go back to the people or person to whom they do belong. It is very likely that MtGox is going to go under from this. I see no reason to ride down with them.