If you trust the Mt. Gox folks, they're now claiming that there was no server hack, just a database copy that some consultant had that got stolen.
If you trust what they're saying, which might be questionable since their business is pretty much going up in flames at the moment, so they are probably desperate to make things appear better than they are...
I hope for their sake that they actually have enough USD and BTC on hand to deal with the mass withdrawals that are coming...