This could potentially be a huge deal:

Get ready for Kindle Worlds, a place for you to publish fan fiction inspired by popular books, shows, movies, comics, music, and games. With Kindle Worlds, you can write new stories based on featured Worlds, engage an audience of readers, and earn royalties. Amazon Publishing has secured licenses from Warner Bros. for Gossip Girl, Pretty Little Liars, and The Vampire Diaries, with licenses for more Worlds on the way.

The Kindle Worlds Self-Service Submission Platform will launch soon and enable you to submit your original works for publication.

I gave a talk a while ago at Nerd Nite suggesting that the publishing platform of the future would find some way to incorporate fan fiction into the platform. I also said that genre publishing platforms should encourage fan fiction by publishing the best stuff as canon and paying the author for the work. This is a smart way for Amazon to tap into a huge publishing ecosystem that already exists and is barely tolerated by the publishing industry. Maybe more importantly, it's yet another opportunity that traditional publishing has squandered.