If there is Bitcoin on the exchange (which is anyone's guess)
That's exactly the point. It is not at all clear there is bitcoin on the exchange.
They are trading this weird GoxBTC thing against GoxUSD and what either of those mean in real units is anyone's guess (for GotBTC I guess you can look to bitcoinbuilder but for GoxUSD there is no organized market as far as I know).
It is totally misleading to label this as a USD vs. BTC price.
At this point they might as well be trading beanie babies against furbies.