Amazon approached through a consulting recruiter, who found my CV on one of the job portals. In my case, it moved forward very quickly - a HR person from Amazon called me and described the team. Then the director of the department (who was in Seattle) talked to me in detail about what the team does and explain the interview process. The HR also forwarded some material about Amazon values and what are the expectations from a SDM, etc.
After the discussion with the Director, there were 2 telephonic rounds - one with an Engineer and one with a SDM. Throughout the process, the HR contacts were extremely helpful and did proper follow-ups. I guess I blew the 2nd round with the SDM. Although, I did get a feeling that the SDM had not reviewed my CV and after 15 mins I had to point out that I have never worked on the things he was asking about and I am just trying to build from first principles. He could not change the track, however and the call abruptly ended. I knew that this was the end :).
The HR reverted within a day with the rejection news. I am thankful for the quick turnaround.