Engadget have released a review of the fitbit networked pedometer. I remember first seeing this about 12 months ago, when it had just launched at techcrunch 50. I like the idea of the device, but it is yet another thing to carry around, and yet another thing to charge.
It makes me thing of the belt valet computers in David Marusek's Counting Heads (Thanks for the reccomendation @doctorow). One day, not too far away, we will have computers that we carry, strapped to our person (perhaps in belt form), that can handle all of the biometric sensing that we want.