Self-replicating machines are an idea that will be familiar to a great number of science fiction readers – but did you know that they were first posited as genuine scientific theory by John von Neumann in 1966? And that now, in the era of nanotechnology, there are only a tiny handful of researchers enthisiastic enough about the concept to continue struggling against the lack of financial support for their work? Michael Anissimov has a potted history of self-replicating kinematic machines which will bring you up to date.