Baby monitor powered by baby

Here's an idea that I thought about when hearing about some of the baby products on the market now (Congrats Ben & Morgan!).

So my friends were telling me about a baby monitor which will notify you when your baby stops moving. The idea is that a baby should always be moving (at least breathing). That idea of constant motion seemed like it might have some energy use...so here's the idea.

1. Create a crib with springs on the bottom of the crib to provide cushioning and some travel in the bottom of the crib (we'll call the surface that the baby sleeps on the "floor" from here on).
2. Suspend a magnet from the underside of the crib's floor such that when the floor moves up and down from the baby's motion, the magnet is moving between either another set of coils, or perhaps you could even use the springs as the wire you need to make this contraption a generator.
3. Now that you have some power being generated by the movement of the baby, setup a wind-up buzzer of some sort that will be triggered when there is a lack of power. So for instance you could use a very low power solanoid to keep the buzzer off until you lose power, indicating the baby has stopped moving.
4. You could install a small battery between the generator and the solanoid so that you could allow the generator to be off for a short time to compensate for short periods of time where the baby isn't moving enough to create enough energy to power the solenoid.

I suppose this is quite primitive and doesn't have much commercial value in this form, but I think perhaps the idea could be expanded, and the lack of something triggering an event seems like it might hold some value....