The big factor will more likely be people that have had their USD or bitcoins stuck in mtgox for over a week, and want to transfer their currency out instead of trading on the site.

Mtgox should also give a few days of grace period before trading starts so people can go in and cancel their standing buy and sell orders at last week's prices. Trading at gox was last at 17 when it closed, but is at 15 now at Tradehill: https://www.tradehill.com/MarketData/. If there are still buy orders in the system between 15 and 17 BTC that buyers aren't able to cancel before trading starts, they will probably get filled real quick until the gox price is down to tradehill's 15. Since all the standing buy orders can be closely analyzed by just replaying the "crash" that got rolled back, insiders already know who wants to buy what at what price.