Dorky Econ Stuff
For all you non-econ majors out there, there's an extensive literature about the use of markets to predict future events. The idea is simple--set up a trading market where prognosticators can buy "futures" of particular events happening. For example, you can now buy a share of the Detroit Tigers to win the World Series for $5 on Tradesports.com. If the Tigers win, you get $10. If they don't, you're out your $5. In other words, the market is predicting the Tigers have exactly a 50/50 chance of winning the World Series. Economists have done study after study, and the results are clear--markets are extremely successful at predicting the outcome of various types of events.
In particular, economists have found that markets are very good at predicting elections.
Today, the price of a share of stock for the GOP retaining control of the House is $3.84, implying that the markets think that the Democrats have a 61.6% chance of capturing the lower chamber.
Not bad odds.