Futures markets

I've become interested in futures markets. Thanks to Professor Ribstein for pointing to a Wall Street Journal article that contained this paragraph about Hollywood Stock Exchange:

Where the MGM executives in "Open Wide" overestimated the opening of "Legally Blonde 2" by $12 million, the HSX market's prediction was within $3 million. Warner Bros. executives overestimated "Terminator 3's" opening weekend by $28 million; HSX came within $10 million. Or take two of Hollywood's most recent shocks: The monstrous failure of "The Hulk" and the stunning success of "Fahrenheit 9/11." The HSX predictions came within about $3 million of each of their actual openings, besting all the professional models. Inexplicably, "Open Wide" ignores this phenomenon completely.

David Tufte links to this same post and says the new SpongeBob movie is going to be big.