An interesting fact thanks to wikipedia:
…The series is translated into Japanese up to Book #36 and sold over 2 million copies as of March 2008. The Japanese version has anime-like illustrations and Osborne commented “Jack and Annie look like Japanese cartoon characters!” …
Before the book signing began, Mary Pope Osbourne talked briefly with her very captive audience. She engaged her audience by involving them in the decision making process of choosing the next topic for more books in the series. The families were also able to vote on titles for the books. This is such an amazing opportunity that she gives to her readers – how cool for a child to be reading one of their favourite novels knowing that they had something to do with the content and title – a sure way to keep kids motivated to read. Watch out for books on penguins, pandas, and rescue dogs. Thank you Mary and Natalie for inspiring and motivating children to read.