It seems it is basically a festival to facilitate the "meditation" spiritual practice. They are nude, but it is done more as a optional factor instead of a factor that directly holds the event together. I think it is odd to see this in that part of the world where may prominent spiritual focuses have had deep roots but I wouldn't expect this event to not have any of these other practices morphed into it.
Personally I would not participate in the mediation practice, as I dont fully agree with it, but the idea of haveing 4 days to hang out in the Negev with like minded people would be hard to pass up.