I feel like this was the best accidental scam and here is why.  If you use the bet quoted above about the "Mt.Gox high price of the day", the person who bet for it to go above $12 can always just place all the bets and then at 10pm PST place a buy order for $12 and win even if the average price was $5.  In the future you guys should use the weighted price. 

tl;dr I am willing to bet at least 50BTC in escrow that Mt. Gox high price of the day will hit $15 within 9 hours!