Ask HN: What to expect at first Hackathon

I currently live in Des Moines as a first year CS student, and I am lucky to be going to: http://thenextweb.com/dd/2012/11/12/dwolla-announces-hackathon-in-des-moines-first-prize-is-a-cow/ tomorrow. It is literally the only one all year I believe, and I have never been to one. I don't have much programming experience, and I have only been flirting with web development for about a year or so and really only know how to do basic things. I am going to take at as a learning experience either way, but should I even expect to do any actual coding? My guess is I would sort of like to be in the background of a group so for the next time I know what to expect. Is this unrealistic? Do you have any tips for someone with little development experience at these kind of events?