HarperTeen is running what it calls A Storytelling Event for Teens by Teens. A panel of authors and editors is involved with the project. Evidently teens will get to submit chapters, teens will get to vote on chapters, and authors will review the highest vote getters. The website says they will be creating "an original short story—one chapter at a time," but I think that's probably a typo, and they're really working on a book.
Participants have until tomorrow to vote on a story premise. Look how well romance is doing compared to action adventure/mystery.