Someone is running a bot on BitStamp that buys exactly 1 BTC at the lowest ask price every minute. (If there is 1 BTC available, otherwise it buys whatever is there.)
Costs about $7700 to run that bot for an hour, let's see how much ammo it's got.

That isn't a bot - that's Bitstamp creating fake trades to pump its volume numbers and feign liquidity.
That is a bot, who's goal is to raise the price on bitstamp, to at least match the price on Mt.Gox. If someone will sell you 1 BTC every minute, what incentive do you have to stoop down to the highest bid price?