While downloadable applications for the iPhone have enjoyed most of the spotlight since they began shipping, momentum is building for apps that run on the Google Android operating system, which drives the first retail Android device, T-Mobile's G1.
One application to catch my eye is Ecorio, a carbon footprint calculator that taps into the G1's GPS feature to track movement. Mode of travel choices include automobile, public transit and bicycle.
Once in motion, Ecorio determines how fast you're moving -- and if you're in a car, how efficiently. Vehicle make and model weigh in as well. Indicating that your ride of choice is a Prius, for instance, helps improve your overall rating more than choosing a Humvee.