How to place your bet:

Go to the website Intrade.com and open an account. After uploading a deposit with your credit card you may start betting immediately. The bet works like a stock option. It is a quite simple principle, there is nothing intimidating:

There are contracts with a nominal value of 10 $, corresponding to 100 points, that is 10 US-Cent per point. You may buy this contract if you believe the event will happen (here: the discovery within a period) or sell, if you believe the event will not occur. It is noteworthy that you may even sell contracts that you do not hold.

As in a stock market, there is a Bid price and an Ask price. If the event happens, the contract achieves the value 100, if not, zero. Thus the actual price is a measure of the percent probability that the event will happen.

Here is a concrete example:
Log in and search the keyword „Higgs“. Among other contracts, you see HIGGS.BOSON.DEC11, click on „trade“. Suppose that the Bid is 40 and the Ask is 44. If you believe in the discovery, you may buy the contract immediately for 44 or place a buy order at 43. If you bought the contract for 44 and the particle is discovered, the price raises to 100 and your win is 56 points or 5.60 Dollars.
But if you do not believe in the discovery by the end of 2011, you may sell it right now for 40 and get 4.00 Dollars or place a sell order for 42. If somebody accepts this 42 offer, you get 4.20 Dollars, but if the particle is discovered, you have to pay 10 Dollars to the purchaser. Therefore, you have to deposit this amount until the contract ends.

This is a screenshot of my order book at Intrade: