While I've never done the dropped-acid-and-burnt-wicker-men-alive thing (at least, not at Burning Man festival), from my understanding the event is meant to be somewhat of an escape from the humdrum of daily life. Meaning, you leave the iPhone at home.
That hasn't stopped a Burning Man iPhone (and iPad!) app from hitting the store in time for next week's festival. The free app acts as a guide to "all the art, camps, and events in Burning Rock City," though reports of it listing the best grass in the area are entirely unfounded. It uses the official API for the event, and is open source reportedly.
While I did moan just a few sentences previously about how iPhones really shouldn't be taken out there, the developers have at least designed it to be used mostly offline, caching all the maps and information when the app is first used. Handy for the lack of reception! [iTunes]