Basically, Engheta has found that sub-wavelength structures can resonate with light, and propagate it (pass it from one place to another). This means that optical computing and processing components can be made very small indeed.
He's currently talking about nano-capacitors, nano-inductors, and nano-resistors, and just speculating about circuits made from combinations of these. But he's already thinking about possible applications in everything from nano-antennas to microscopy.
The coming ability to build lots of precisely engineered nanostructures in heterogeneous patterns (you knew there was a molecular manufacturing tie-in) will accelerate such research and its applications. Our ability to process light today might be comparable to the ability of flint knappers and cavemen to make and use knife edges--we do it by banging large hunks of energy together, and the results are crude but functional for some purposes. I won't even try to speculate on what we'll be able to do when we can guide individual photons through sub-wavelength processing machines.
Another Physics News Update story reports that ice can be made to form at room temperature if a high electric field is used to align the water molecules. How high? It was thought that it would take a billion volts per meter. But it actually only requires a million--which means a volt per micron should do it. That's not even nanotech, but I thought it was cool anyway.