It's better to not use MtGox as a baseline price anymore, it's at about $20 higher then any other exchange due to the fact that you can't actually get your money out of it ATM. Check the btc-e graph for a better view:
One cool thing that has happened over that several months is that Mt Gox has drifted down to a market share of around 30% of the total trade volume (generally speaking; ocasionally this trend weakens on days with huge swings, but less often than before). It is good to see more healthy exchange competition.
http://bitcoinwisdom.com/markets/btce/btcusd
(They both show the same trend, I'm just being pedantic)