These are really interesting questions. I had a withdrawal request from June that was not met. Responses they gave me kept indicating another 2 or 3 week backlog, as per their public announcements. Eventually in early August I gave up, and took the price hit on transferring out via BTC. A bird in the hand is better than a dead one in the bush.

I agree this smells of Mt Gox adopting some highly unethical practices to solve cash flow issues. Although this is unproven, Mt Gox has given no evidence of what it has actually paid out in withdrawals once these delays were announced, which banks they have new arrangements with (if any), etc, so they have not been very transparent and therefore invite skepticism even if unfounded. I would be interested to hear who has actually received withdrawals, and how long they waited.

The arbitrage seems easy unless you take into account that we really don't know how much longer the problem will go on for, given past statements have not been met (at least for myself). Until Mt Gox demonstrate otherwise it is possible there could be a bigger danger lurking behind the scenes.