[_jal]

That's the Extropian "Utility Fog" concept.

A more direct science fiction forerunner of this is Bruce Stirling's _Islands in the Net_ (1988). There is a scene where cheap explosive drone swarms are used in terror attacks.

And of course, there's the famous first line of _Count Zero_.

"They sent a Slamhound on Turner's trail in New Delhi, slotted it to his pheromones and the color of his hair. It caught up with him on a street called Chandni Chauk and came scrambling for his rented BMW - Its core was a kilogram of recrystallized hexogene and flaked TNT."