CONSPIRACY THEORY TIME. What if Mt. Gox didn't really lose a post-Panamax boatload of Bitcoin (just a small amount)? They're just manufacturing a panic so they can buy Bitcoins at fire-sale prices, declare "We have all the BitCoin we need after all, we fixed our bug, everything's fiiiine" and maybe even turn a cash profit on the upside?
If there was any evidence of that they'd go to jail for a long time - even if bitcoin is not directly regulated, I'm sure there are still some anti-fraud regulations that would kick in...
They could actually have lost the bitcoins. They could be still having technical problems.
Fennecfoxen's theory could be illegal market manipulation, but I wouldn't be surprised if the BTC market is weird enough that it doesn't fit under the laws against that. Or at least that it'd be such a mess to prosecute that prosecutors would all find something better for their careers to do.