No, there is no way to get your US Dollars out of Mt.Gox, after you sell you BitCoin, in a reasonable timeframe. Supposedly they only process about 10 total USD wire transfer withdrawals per day. There is also a question of bankruptcy risk as it is common knowledge that the US Government seized several million dollars from MtGox earlier this year.

Anyone that quotes MtGox as the reference bitcoin price almost certainly has little experience trading bitcoin. Bitstamp is a much better reference price or if you want to be US centric CoinBase.

It's not that arbitrage opportunities don't exist in the Bitcoin world. There are some rare and fleeting ones. This just isn't a good one.