One big thing distorting the Mt Gox recent bubble was the ability to game the averages by making a bid you had know way of backing up. I think this is a big recent for the recent attack. Per MtGox, their statement about changing this, starting Wednesday:
Orders will only be accepted when there are enough funds available in your wallet! Dear users, starting on April 17th we will be rolling out a minor change on how people place orders via the Mt.Gox interface. Until recently, anyone could place a buy or sell order for Bitcoin, regardless of how much funds were actually available in their wallet, resulting in an order showing a "Not enough funds" error status in the Open Orders list. Starting on April 17th, this counter productive scenario will no longer be possible and will be automatically rejected before validating your order; until you have enough funds in your wallet to match the order value. While this change should only affect a minority of users, it will however have a major impact on our trading platform and improve our system overall performance.
It must have been easy for the bad actors to inflate the price, under these conditions. Of course, if I'm missing something, that wouldn't be the first time.