I haven't heard anyone mentioning what I speculate happened, so
time to throw my voice into the crowd.
We have a situation where MtGox has without warning disabled bitcoin withdrawals, then a couple days later announce/accuse a hole that permitted someone from getting more bitcoins than they deserved.
Days later another
popular "exchange" said they were affected by the same vulnerability and had their entire wallet stolen by the process.
MtGox states that they are in full compliance with Japanese law, which requires all exchanges to be fully solvent while they are running.
What I speculate may have happened is that MtGox's online wallet was completely drained by this exploit and that may have caused bitcoin withdrawals to end. They may have been smart and had an offline wallet as well (so they aren't completely bled dry) however being a very popular exchange they likely lost a large chunk of their coins in the process and are now bitcoin-insolvent. They are still operating within the law in this case because Japan doesn't know what bitcoins are yet and they are still fully fiat-solvent.
It also means that their goal would not be to attract more dollars, but try to find some place to get more coins from. Metering bitcoin withdraws at the beginning would make sense (until they run dry). I believe they're also scrambling over trying to improve their code to plug the hole, especially with feedback (in threads on this site) as to how low their server code quality is.
