b00le writes "The BBC says that the scientist many regard as the father of nanotechnology has backed away from his famous claim that runaway nanomachines could turn the planet into 'grey goo'. Eric Drexler now says nanomachines that self-replicate exponentially are unlikely ever to enter widespread use. So that's all right, then, but he also said 'tiny machines would need close control' - which not everyone would agree with. I always imagined some kind of emergent behaviour would, er, emerge." Bill Joy is still suitably pessimistic.