There are some serious lessons to be learned here for both "Market Moving Exchanges" and you whining "traders". Lessons already learned by long-time precious metals traders about an alternative currency/commodity, the mining equity stocks, and how sovereign nations and international banks(ters) manipulate markets to their own interests.
The bitcoin itself is encrypted, digitally strong, and distributed non-centrally, which are it's strengths to prevent manipulation of itself. Now think long and hard about any nation-state, or central-banking currency, that perceives the bitcoin system to be a threat. They will attack the exchanges. They will sow distrust, and attempt to manipulate the MARKET to crash the bitcoinage. To lose $8.5 million to achieve their goal of market disruption is pocket change to these powers! They can print more! ANY marketplace/exchange that gains enough volume (like Mt.Gox) to seriously move the market price WILL BECOME the target of a market-moving attack from 'The Powers That Be'. It therefore behooves the Market-makers/exchanges to be as paranoidly secure in their systems as is humanly possible. You WILL BECOME the object of nation-sponsored hacking attempts and subversion you cannot imagine. Strive for the security of the bitcoin itself in your market systems. You are... literally... up against "all the money in the world".
Market Exchanges should implement safety systems to prevent 'flash crashes' and market-manipulating high volatility moves. Even the NYSE has 'circuit breakers' implemented to prevent such moves. Take a lesson there.
Stocks themselves and currency moves are routinely manipulated with unlimited paper backing to move markets according to perceived 'national interests'. It is not possible to 'naked short' bitcoins like is routinely done with equity stocks, so these monsters must accumulate large... huge... piles of bitcoins in accounts in order to manipulate the market. EXCHANGES SHOULD LIMIT THE NUMBER OF BITCOINS HELD IN ANY ACCOUNT TO SOMETHING LESS THAN MARKET-MOVING VOLUME. This will slow the manipulators just a little. Then they will coordinate attacks from multiple, smaller accounts. So EXCHANGES SHOULD IMPLEMENT 'CIRCUIT BREAKERS' much like the NYSE to prevent large percentage market-volatility moves. Stop the trading and enforce a 'time-out' cooling off period before resuming trading. This also gives the market exchange time to investigate the source of the market volatility moves, and isolate troublemaker accounts. Many anarchists say there should be NO LIMITS on trading. I agree in principle, but recent history demonstrates that this leaves the marketplace vulnerable. I say to MODERATE the market, while keeping it free in smaller volumes. Just as an unmoderated forum will degenerate into chaos, we have now seen how an unmoderated marketplace WILL crash and burn at the hands of agent provocateurs. Remember... you are up against "all the money in the world".
So you 'traders' whine about your corrupt (at least on one side) trades being reversed. Take a lesson from stock and commodity traders. It is not a 'trade' until the exchange clears it and lets you take that money. Sometimes that takes several days before clearing. Until then, the exchange is in control of your funds and trades. You traders who made a killing and withdrew your funds/bitcoins to your outside wallets are the smart ones who 'cleared' your own trades.... and did so in much less time than any traditional commodity exchange would allow! Count your blessings!
I'm a longtime goldbug sufferer at the hands of the national manipulators. Done the research and seen it all. I don't play in paper-manipulated stocks nor paper gold promises. I collect the real, physical thing out of TPTB reach. I began accumulating bitcoins because I believe it is the liberty currency of the digital future. I treat it the same way as a gold coin. I made my last buy at 17.70 and then transferred most BTC out of the exchange to my wallet that is kept offline normally. Apparently this was just hours before the crash. Mt.Gox still has some of my USD in account (I hope!), but I carry the account with the idea that I could lose it all, so I keep the balances minimal. Any smart trader should do the same. Fund only what you are willing to trade (or lose!) and get the rest out of the 'brokerage account' and into your secure possession. Let the buyer beware. Any account holder with large sums in their account is either stupid, or looking to make trouble in the marketplace.
It is time for the bitcoin marketplace to face the stark reality of an unfriendly central banking world that wishes the bitcoin dead and buried.