From the Berkeley Robotics Department.
Economist Tyler Cowen asks "What is the political equilibrium when insect sized drone assassins are available?" All answers are unpleasant. This isn't even the Singularity, just a seemingly very likely possibility as mobile electronics continue to get smaller. They don't even have to be autonomous.
The smaller that automation gets, the more potential for disruption. We vastly underestimate the disruption from small autonomous flying robots. You'll move (or run) if you're walking somewhere and see bees. And bees are stupid and mostly want to ignore us, and can't even kill us.