Fiction to fact
And we live through the process of science fiction turning into science fact again. Read the 2002 novel Prey by Michael Crichton and swarming nanobots are to be found therein.
Researchers have taught flying drones to behave like birds, clearing the way for further development of technologies to marshal swarms of unmanned aerial vehicles. In a paper titled Outdoor flocking and formation flight with autonomous aerial robots boffins from Budapet's Eötvös University Department of Biological Physics …
You are late with your welcome by 20 years.
http://en.wikipedia.org/wiki/P-700_Granit
See the guidance mode section.
While the welcome to these particular drone overlords would have been very warm indeed, it would have been very short too. On the order of fractions of a second to the tune of Pink FLoyd's, 'Two Suns in the Sunset' .Thankfully, it has never been fired in anger.
I could potentially give them S&R after disasters in an urban area but I can't think of many civilian uses for a flock of quadcopters at 50-100m range, though if they can extend that then yes it may be useful. Imagine TV weather copters being replaced by multiple drones to give greater flexibility or with the right software even a composite overview. Even for militaries though I think unless they're willing to have dozens of them up at once for a truly absurd coverage area more than 3-5 for recon and tracking purposes is probably excessive, and definitely excessive if they're only going after single targets as is more commonly the case today with all this "low intensity wafrare" crap.