Maybe, but as a programmer it's always nice to have someone paying attention to the other things you don't like doing, like making a good presentation, mocking up designs, etc. Esp since a lot of people don't pay any attention to that stuff it can be quite worthwhile.
I don't expect to be much use at the hackathon. I'm going to get more involved with the startup community and contribute whatever I can -- ideas, presentation, etc.
You'll be plenty valuable, don't worry. Sometimes the business guys go out and do market research, get preliminary letters of intent signed, do presentations, etc... Enjoy the experience, it's completely worthwhile and rewarding. (note: I'm a technical guy, been to a couple of these types of events, and know the value non-techs bring to the table)