From the Burning Man "Press"
Burning Man is a private event held on public land. Because of this, all professional mediaâ€”which includes both still and moving image photographers-- are required to sign professional use agreements once a project has been reviewed and approved by the Burning Man Media Team.
You don't need to do this with a still camera for personal use, and you can bet a lot of those video's you see on You Tube didn't have one. They may come after you if you try to make money off the images, they will definitely come after you if you try a "Girls Gone Wild" type of thing.
This comes up every year, but I'm too lazy to look up the old threads right now, so here's a basic thing to remember:
ASK before taking any picture of a person- male, female, young, old, costumed or naked... doesn't matter. If they're the subject of your shot, ask them. If they say no, respect them. There are plenty of other people to photograph.
Most people won't care and will pose willingly. I've had a couple of people say no to pictures, we have a nice chat, I move on.
If you're getting a crowd shot, not so much a worry.