I think to a certain extent Bitcoin is manipulated, but what else do you expect with this low volume? May be One day, we will have surely bigger volume and will not be so easy to be manipulated like now, but until that we can just see the whales. Don't forget that also many big institution enter/will enter this market, also Nasdaq will launch their exchanger next month, so more volume is coming.
Mt.Gox fact it is bad, and they don't care about the market price, they just want some money back selling this large quantity of btc left.