With staggering swiftness, the mobile phone has become a fixture of daily life in almost every society on earth. In 2007, the world had over 3 billion mobile subscriptions. Prosperous nations boast of having more subscriptions than people. In the developing world, hundreds of millions of people who could never afford a landline telephone now have a mobile number of their own. With a mobile in our hand many of us feel safer, more productive, and more...