As awesome as it sounded, there's just too many problems with the drone idea. I fly these sort of things for fun. They do not have the range or lift capacity to be worthwhile in a delivery role. It would be MUCH improved if the drones were configured like a Boeing V-22 Osprey and could transform between VTOL and forward-flight modes. But the examples they used were generic multi-rotors, no good.
Not to mention the automation - how will the drones map addresses to physical GPS coordinates? At best they'll get within fifty yards of the house they need to be at, going by address and postcode. Thereafter you're relying on this thing knowing what to look for in order to find the right address.
Only way to solve it would be by requiring customers to input the "landing location" they want when they place their order. If you determine your exact GPS coords, it should be able to land within a couple metres of your front door.
I really hope this becomes a thing, but I doubt it will, certainly not in 2015. Would love to be wrong though.