I have been having this weird problem where my iphone's bluetooth turns on by itself and I have to keep going into settings several times a day to turn it off. I dont have anything paired to it. I didnt find anything here on Macrumors but a few people on the apple board have experienced this:
http://discussions.apple.com/thread.jspa?messageID=11170016
http://discussions.apple.com/thread.jspa?messageID=11170016