Just a piece of speculation, nothing that I advocate, but I believe I'm not alone to think about this.

Gox is likely sitting at nice stash of btc, and if they are insolvent, they might want to sell large portion of btc at the highest possible price.
So gox manipulates the price and makes others to follow, until volume there is enough high to make them so.
Rising price can also induce more interest in bitcoin and thus influx of newcomers buying into btc (most of them may not be buying at gox, but still easing their effort by eating sell walls at other exchanges). Also, here could be helpful the secondmarket news, to which the rally would be accredited in media, thus finding more plausible and bullish explanation for the raise.
Where that goes is clear. In later stage of rally gox starts to dump (not only on their own exchange of course). Also more players exit their positions. With gox losing its market share and ask sum at other exchanges growing, the market peaks and a crash follows.