The Bruning Man festavil is getting a web based API. The API geives application access to maps of Black Rock city and information on events and camps. Data can be handed back as JSON or XML. Most of the information can be accessed as a list of things (e.g. camps) or can be looked up by ID. There are exceptions, for example events can be searched by start time or end time or both.
There is also an iPhone App for burning man which offers pretty much the same information as the API, and thats not it. There is an initave to provide SMS service thanks to OpenBTS and also the the Virtual Playa project.