So...you have a new book out?
Yes!!! It came out on August 24th, 2013. The new book is Where Dragons Dwell.
Here's a link to the blog page for it: Where Dragons Dwell. That page has links to where it's available, etc. But to save you a step or two, here's a link to it on Smashwords: Where Dragons Dwell. (You can read a sample there.)
Where Dragons Dwell is not part of the series, and it is quite different from those books. Age-wise, I would say it's not for elementary school readers unless they are not frightened of things like dragons (and the violence of killing them) and unless they are able to handle fairly complex sentence structures.
But--dragon-violence aside--it is still a happy story with a lovely message (if it were part of the series, it would be "A Tale of Hope").