There are two parts of this story that are pretty innovative.
1. Teeny tiny robots.
"The idea is that stretching a silicone rubber band just nine microns thick can enable these microrobotic devices to move by catapulting themselves into the air. Early tests show that the solar-powered bots can store enough energy to make a 7-millimeter robot jump 200 millimeters high. "
2. Using these robots as a 'mesh' sensor array network.
"...Berkeley Smart Dust Project, which was set up to build distributed-sensor networks that can communicate over long distances using mesh networks, Bergbreiter aimed to give these kinds of sensors useful mobility. She created a tiny solar-cell array to power the device, a microcontroller to govern its behavior, and a series of micro electromechanical systems (MEMS) motors on a silicon substrate. The last were used as part of a ratcheting mechanism called inchworm motors, which draw two hooks apart as a means of stretching the rubber band. "
Great article with lots more detail: http://www.technologyreview.com/Infotech/18477/page1/