Micropower generation/power harvesting

Linear Technology lists the LTC3108, an Ultralow Voltage Step-Up Converter and Power Manager than runs with an input of just 20mV producing a 5V output to power things such as low power wireless devices and processors. Surely there must be an application for such a device in ultra-QRP portable equipment? Imagine, where can you find 20-500mV of noise from? 50Hz crud in the ground, a thermo electric sensor, solar cells etc. I wonder who will be the first person to make a QRPp uW beacon powered using the 50/60Hz buzz available between a couple of earth electrodes in the ground?

Power harvesting IC - runs off 20mV produces 5V

This week's Electronics Weekly has a link to Linear Technologies new power converter IC (LTC3108) that can run from 20mV and deliver 5V. It is designed to be used with Peltier effect devices and similar sources of low voltages, but it could be used with the DC power derived from a crystal set.