its been clear for a while now that bitstamps is get more and more volume coming from mt gox
the price difference is a result of this shift
it could stay that way for a long time... buy now
A volume-based metric I place some trust in, confirms that: there is substantial buying pressure on bitstamp, even if the price gap somewhat obscures this fact.
First the similarities: daily A/D continued to rise on both bit and mtg, well after the April peak, and throughout the initial correction/bubble deflation. It peaked in mid-June, then gently started sloping downwards. The corresponding price action was the recent downtrend that took us from ~110 to ~70 (mtg prices).
Now for the differences: as of early
It's as if all the btc optimism migrated from mtgox to bitstamp. No guarantee that this lasts however, if mtgox manages to solve its fiat problem in time.
EDIT: corrected mistake