I am not sure weather it is a proper question to ask out here but it is really bothering for a while. As the official website writes:
The Rails Rumble is a distributed programming competition where teams of one to four people, from all over the world, have 48 hours to build an innovative web application, with Ruby on Rails or another Rack-based Ruby web framework. After the 48 hours are up, a panel of expert judges will pick the top ten winners.
One thing I don't get is how judges make sure that the app was made in the given time constraint. The quality of apps is so magnificent that I am really skeptical that such elegant apps could be made within 48hrs, even if you have planned it straight out on paper.