A company called Carbon Diem has developed an application for Blackberries and some Nokia phones that enables the user to measure their carbon footprint in real time with the use of the phone’s GPS system. The system is able to measure the speed you are traveling (using the GPS) and make certain assumptions based on the information it’s gathering. For example, if the phone tracks that you’re traveling between 5 and 15 mph for 30 minutes it can...