For the general concept behind The Rabbit Room, read http://www.rabbitroom.com/about-the-rabb
In case (like me) you don't know who Andrew Peterson is... he's a contemporary Christian musician that has been around for over 10 years. I hadn't exactly heard of him, but I was very familiar with one of his songs (Dancing in the Mindfields - YouTube) having heard it on K-LOVE.
Anyway, he is also an author of a fantasy series of books. He just released the third, and there is one more currently in the works. Reading his blog entry made me curious about his writing, so I ordered the first book of the trilogy.
It's similar in style to the Harry Potter series, and I really enjoyed it. It too is targeted at a younger age group, but I still enjoy a leisurely read. I liked the book so much that I have ordered the second two books that are out. Hopefully they'll come in before I head to Massachusetts on vacation...