Those are my USD, not yours . . .
This is not at all clear under US law, which would presumably apply given Bitfloor's ties to the US.
Au contraire, US law is perfectly clear on the matter:
These are all things for the legal council (and if it goes to U.S. court, the judge) to decide in order to figure out what actions are appropriate. That's where the "due process of law" comes in. You're entitled to your process, BitFloor is entitled to theirs. BitFloor seeking legal council is where he ensures that he is acting in a way most within the law. Your process would be serving BitFloor and/or suing them.
Things are not that simple that withdrawals can happen just for the solvent parts of the business held; welcome to the world of BitCoin, where everything is without absolute legal precedent (yet). If a legal precedent can be set that the BTC has value, it would be illegal for them to use any portion of the assets (including remaining balances held for what wasn't hacked) to pay out to anybody until the appropriate process on reimbursing has been determined in court.
This WILL not be a quick process. The only quick process would be if the coins were returned by the hacker, or if someone invested BTC in BitFloor in exchange for ownership (or a portion of). I'd imagine this case (albeit not a likely one) is the one that BitFloor is hoping for the most.
Best case for USD holders (and worst case for BTC holders) is that his legal council (or the court system) determines that BTC will be considered "worthless" and that USD should be distributed to account holders as it's the only part of BitFloor that needs to be legally held solvent. However, I can just about guarantee that if this happens, anyone holding a large amount of BTC will file an injunction and appeal, which will almost certainly prevent payout of USD funds from happening quickly.
Hang on folks, this is likely to be an interesting one, especially since it's occurring in the oh-so-litigious US.
You are assuming facts not in evidence:
1) Bitcoins have not been legally recognized as anything other than magical internetnerd tokens.
2) Bitcoin is an experiment, there is no implied warranty or service-level agreement.
3) BitFloor has not formally declared bankruptcy, which is the
only way they can legally hold USD without the owners' consent.
4) While bitcoin is uncharted legal territory, regulations for transactions regarding USD are well known and quite settled. You can't detain or steal legally-recognized USD "because bitcoin."