Salon has an interview with Lise Haines, author of Girl in the Arena, which, at least in the interview, comes off sounding like The Hunger Games. Some of the commenters thought so, too.
Though Bloomsbury states in its catalog that Girl in the Arena is Haines' debut novel, according to the interview and her website, she's written two others for adults. In discussing why it was published as YA, she tells Salon, "...I just wrote the novel I had to write. I let others sort out how to sell and market it."
She's not the only writer who has said things like that. While I can see those writers' point, it seems to me that attitude comes from a belief that writing is some kind of mystical and otherworldly experience, an art that can't be defined. My belief is that art involves craft and that writers should have control of their craft and technique and know what they're writing. Thus, you should know that you're writing a young adult vs. adult novel.
On the other hand, I have to admit, if I wrote a kids' book and a publisher said, "We want to publish this as adult," I'd probably say, "Go for it." You can control your work while you're working on it, but afterwards things get a little murky.