The truth is, drone delivery was discussed already here on HN. A lot of the details were already envisioned and suggested.
A lot of the commenters on this thread think it's a new idea or its's new here on HN. This is a good PR move for Amazon(edit: equal to Google's self driving car in PR power). It's likely they got inspired by some of the HN discussions. I hope they don't invent silly patents around it, such as "one flight delivery".