The Verge has a long look at the latest improvements to Nike's Nike+ fitness system, which uses sensors in your shoes (and on the company's very popular Fuelband peripheral) to calculate fitness and workout information, and attempt to help keep you motivated while working out. The whole system sounds very complex: There are multiple sensors in the shoes designed to track exactly what you're doing and how, and all of that movement is broken down into a single number that aims to push performance.
Unfortunately, Nike is somewhat skittish when it comes to actually explaining what that number means -- while getting out and moving around will almost always be good for your health, Nike's reluctance to pin down
