Diamagnetic Micro Manipulation (DM3) uses tiny magnets that move under a circuit board, to get the micro-robots to follow a set pattern based on a set of preprogrammed instructions. The system can be set up so just one or a couple of robots are working together, or you can have giant groups of them moving together in sync like some bizarre gymnastics routine. Despite their tiny size, the robots can move up to a foot in a single second, so they can haul around your micro manufacturing supplies pretty swiftly.
SRI says that DM3 can be used for prototyping parts, electronics assembly, biotech lab-on-a-chip experiments, and assembling small mechanical systems in hostile environments. Eventually they plan to scale up the technology, by developing a manufacturing head containing thousands of the little buggers that can build much larger assemblies.
Magnetically Actuated Micro-Robots for Advanced Manipulation Applications