Yes, you can. Check out Slate, which is keeping track of several websites that allow you to wager (or invest if you will) on different candidates and their chance/price/odds. You can follow the trends in these over time on Slate’s page. Many, including DARPA, belive prediction markets are very effective at predicting events, much like publicly traded stocks predict the future of corporations. In fact, the prediction markets were, over time, excellent at predicting President Bush’s win over John Kerry.