If and when withdrawls start being processed again, I expect that arbitrage would slowly come back online, narrowing the present gap between Mt. Gox and other exchanges from its current ~8% to something more like 3-4% (perhaps less, depending on the number of people with Trusted verification on Gox). I expect that this won't cause too much drift in the price aside from reconciling the exchanges, since any money that wanted to leave the system probably either has done so or hasn't been spent on anything but "get in the withdrawl queue" any time recently, and deposits have presumably been going to other (cheaper) exchanges.