I was just watching a ted talk by Alan November
http://www.youtube.com/watch?v=ebJHzpEy4bE&t=11m10s
where he talks about a student who uses the site, as many do to write in the style of an author. Apparently there are a lot of kids who do it, motivation is intrinsic, their writing improves but most importantly they choose to do it and it is because they are published authors writing for the world, they have an audience, who reads there stuff and interacts with it.
one of the finest collections of author/illustrator videos I've ever seen. It's a staggering - interviews of pretty much every key figure in modern children's literature. What you see below is just a fraction of their author video library. You can access the videos two ways: