Joab Jackson from Government Computer News (GCN) wrote in his October 30, 2008 article: "Texas Instruments demonstrated a number of handheld microsystems here that draw all their power from the surrounding environment, either from light or vibrational energy. Such devices could serve as platforms for running environmental or other types of sensors in remote locations."
Read the whole article here: www.gcn.com/online/vol1_no1/47468-1.html. It's a good description of TI's demo. Also, check out November Embedded Systems Design's 2028 articles (posting on November 1), in which many of the authors agree that energy harvesting has a big future and great promise.