I think its 4 weeks, with prizes every week. The odds of winning are slim, but the real prize is beating your friends.
Even at slim odds though, a few hits and you could be in the running. The game plan is to go with 1 or 2 stocks that you think might hit. So, say you have a stock that you know has an FDA approvable letter coming out and you score big on it and the was able to immediately invest in something else that gets hot. It really only takes a few minutes to screen some stocks that might get hot and then hope for the best.