Physorg.com is reporting that scientists led by Xiang Zhang at UCB have a paper in Science documenting the ability to do "optical" imaging in the range of 40-60nm. They are using 365nm UV radiation and a silver film "superlens" with a negative refractive index to transcend the normal diffraction limits of optical imaging. Their results are nearly an order of magnitude smaller than conventional optical microscopy methods. Optical imaging is faster than electron microscope imaging because you don't have to scan the e-beam across the material being imaged.
One application which may push its development would be the direct imaging of semiconductor chips as the pass through the next two generations of photolithography at 65nm and 45-40nm. It is also worth noting that at these dimensions one could probably make a movie recording the motion of Drexler's classical assembler arm performing assembly processes.