The new book is called "Star Reporter"!
I think this is pretty cool!
See, when you buy the book click on the Unlock Coins Badge, then click "I have a Book". After that, Click the book you have, and you will be asked to answer a question, like: "What word is on page 6, 9 words from the left on line 8?"
If you don't have a book, Lime Cheats is going to help you! We have a Club Penguin Book Codes Page, with answers for the first four books!
We will add some codes for the new book in a few weeks, k?
When you unlock a book, you get a blue book hand item (If its your first book you've unlocked), and a big bag of coins!
~Me12101 lime cheats president