All three products work with the Nike+ shoes, which contain what a pc.com review calls a, "a very small 2.4-GHz transmitter that plugs into the iPod nano's dock connector and a small, flat sensor that you slip into your right shoe underneath the sock guard. The two pieces communicate wirelessly with each other; the sensor sends complex waveform data about your speed, which the iPod then translates into distance and other measurements."
The measurements include time, distance, distance remaining, pace per mile, calories burned, and more. You can even challenge up to 50 running buddies via e-mail with 4 different types of challenges: a distance race, the most miles, the fastest run, or a team goal. Who said running is a solitary pursuit? Not in the 21st century, it isn't.
For those holdouts who don't own an iPod (myself included) the Speed+ is available for $129.00. It's basically a Flight+ without the iPod controller. It comes with USB connection to upload to your computer all of the training information gathered by the Nike+ Shoe sensor. (All four products were supposed to be available on May 1, but I still haven't seen any of the models on Nike's Nike+ eStore. I will post a notice when these products become available.)
More information from gizmodo.com.