There is a slightly new development in this situation. Over the last 1/2 hour or so, it seems that Amazon has pulled these books and made them unavailable.
My guess is, initially, they sought to price match the iBookstore and/or Smashwords. Afterwards, they realized that "punishing" the authors by those means really did very little to dissuade/upset them.
Hopefully, they won't decide to yank all of the downloaded copies, out of spite or something else. I heard they've done that before, in different circumstances.