Publishers Weekly has published an article about the possibility of Amazon's plans to sell used e-books. Whether is speculation of the part of Publisher's Weekly or the story is based on actual hard news I have no idea.
I do believe if this comes to pass, it will change the world as self-published authors know it, particularly in the Kindle market.
In addition to reading the article, I would take the time to read a few of the comments as some of these give a little insight into whether or not this would be legal piracy on the part of Amazon.
It appears Amazon has been granted a patent that would allow Amazon to have the means to sell used e-books. This seems to imply that authors whose work has been sold in Kindle format would lose the ability to collect royalties on their works.
This seems to all hinge on the results of a lawsuit currently in the courts that will define this issue as it pertains to digital content.
Here is the link once again: