I finally got my USD withdrawal and been arbitraging with everyone else.
Did you actually get USD for Gox today?
The reasons I'm doubtful of the "working Gox arbitrage" theory is (a) the drop was precipitated by a large market sell order on BitSamp (JorgeStoffi confirmed this several pages back), and (b) would we not expect to see a rise in the price on the non-Gox exchanges caused by people re-buying the coins they're selling on Gox?