The following is a link to a BBC news article that claims the iPhone keeps a log of user position and downloads the data in an unencrypted format to the computer connected to iTunes. Apparently this is in the Terms of Use, but still it smacks of Big Brother. And I don't like the fact somebody could access this file.
http://www.bbc.co.uk/news/technology-13145562
http://www.bbc.co.uk/news/technology-13145562