[jcfrei]

withdrawing USD from mtgox and transferring them to btc-e takes roughly two hours, depending on which payment processor you choose. okpay is usually pretty fast, but you loose about 50$ on commission. furthermore unless you are verified on mtgox, you've got a withdrawal limit of 1000$ per day. add to that the time interval during which your money is locked up either in the blockchain or the payment processor and you end up with substantial risk between the trades.

EDIT: This only worked until the end of may - I've just noticed that OKPAY withdrawal is no longer an option: https://www.mtgox.com/pdf/20130528_okpay_statement.pdf