I guess you mean "it's down". Still 250 BTC strong. Whoever put it made a large buy with no slippage thanks to the predictable force downwards after the rally. Quite smart person.
I doubt it. I guess that person put an "instant" order, which is not the same as mtgox's market order: it puts the order at market price and then moves it every 10 minutes. I guess it's the same person who is selling now. If you want cheap coins, sell all now and put an order where that wall will end.
edit: it's gone. Someone bought it.