This 60 Minutes video is a very interesting insight into Amazon's distribution centers etc, including some on the drone research project.
For me it's very telling how they are pushing every aspect of the business to get a better edge. For example they have computer algorythms to optimize how shelf space is used, and they now can stock twice as much in the same space as they could five years ago. This is not your father's mail order company, and it explains a lot.
Oddly, it seems 60 Minutes continue using Flash for their videos, so they can't be viewed on tablets. More than that, on my laptop it failed to play on Safari and on Firefox, only the newest version of Chrome played it.
Update: If the video fails to play, TCGirl found it on YouTube.