Note the Gox price (purple area) is on a different scale to the arbitrage values. Mouse over the chart to read the price difference figures in the top left.
For more information on this situation, I recommend this blogpost by a trader here (please remind me of your nick): http://theblogchain.com/2014/01/24/mtgox-is-mtvesuvius-the-full-story/
Here is another look at the spread between Gox and other exchanges: http://www.coinometrics.com/bitcoin/dispersion
This website shows stats on failed transactions from Mt. Gox: http://thegoxreport.com/
Finally, this chart shows highly lopsided bid to ask order depth on Mt. Gox: http://www.blockchained.com/depth_mtgox.png
For these reasons, I consider it risky / illogical to follow Mt. Gox as a leading market, no matter how their high price goes.