The FAA has issued a special "experimental airworthiness certificate" to Amazon, allowing the company to conduct outdoor research, testing, and training of its Prime Air delivery drones.
Amazon announced it ambitious drone plans back in December of 2013, but it filmed the highlight reel video for that outside the US to avoid running afoul of FAA regulations. A year later it threatened to take its operations overseas if the FAA didn't allow it to begin performing outdoor testing.
Amazon can move out of the lab and into the field
After several years with little progress, the FAA has been busy of late. It took a big step last month when it published a proposal for new rules to help legalize commercial drone flight and has been granting a number of exemptions to different companies that want to begin field testing with flying robots.
Unfortunately those new rules, and the exemption granted to Amazon today, insist that the drones remain within line of sight of the pilot at all times. In Amazon's case they must also have "at least a private pilot’s certificate and current medical certification." Those kind of restrictions make sense for initial testing, but would definitely prevent the rollout of any scaleable commercial operation if they remain in place, since they severly limit the use of autonomous drones over a meaningful distance.