The advent of the drone, currently small expensive and of limited performance, is just the thin end of a potentially very big and dangerous wedge. Just look at the exponential expansion in mobile phone capability to see what can happen and Amazon, for example, are already looking at load carrying drones. Strict regulation is needed NOW to limit the weight, altitude and range of these devices and their operation should strictly licenced.
Like others I can see the threat to commercial aircraft of a bomb laden drone hovering on the glidepath, invisible in cloud or at night. What about the threat to General Aviation? Light aircraft operate mainly in the altitude range achievable by drone devices and the consequences of a collision with one are even more likely to have a serious or catastrophic effect than on a large commercial aircraft.
I would like to see drone operations restricted to a maximum of 250ft agl, day only, with a max weight of half a kilo. Operation should only be allowed to licenced operators and not within 3 miles radius of any airfield or licenced strip. Like a virus, these things are out there now and must be controlled before something seriously bad happens.