I've been wondering about why people do this sort of thing, so thanks for answering that.
I found it curious that Startupbus, which I believe is going on right now, seems to never have had much traction on HN, and when it did, it appeared to be astroturf. It seems like an unforgettable and intense experience, but combining a hackathon with cabin fever and gross bathrooms just doesn't seem like a lot of fun.