While this is sort of interesting, how is this better than a pair of AAA batteries, or even coin batteries? If this thing only generates enough power to run some sensors, I would imagine a small battery would last years in a similar setup, and cost orders of magnitude less.
There's a very similar startup that's been around for at least a few years:<p><a href="http://solepowertech.com" rel="nofollow">http://solepowertech.com</a><p>I don't think they generate electricity from the swing of your step, but they certainly harvest the shock force.