The BBC has an interesting article/video about the development of nano-motors to power tiny robots. The innovation, which has applications in surgical procedures, was reported in the February 2009 issue of the Journal of Micromechanics and Microengineering. I believe the article is titled, "Piezoelectric ultrasonic resonant motor with stator diameter less than 250 µm: the Proteus motor," and is authored by James Friend and colleagues from the Micro/Nanophysics Laboratory at Monash University in Australia.
If you want to read the the original journal article, you're in luck! The University of Washington has a subscription to the electronic version, which means the Journal of Micromechanics and Microengineering (from 1991 to the present) is available to UW students, faculty, and staff online.
According the the BBC article, the "researchers' prototype measures a quarter of a millimetre wide - not much more than a couple of hairs side-by-side, and 70% smaller than the previous record holder."
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