Buy the book
I've bought Peter-Paul Koch's book.
I've been a fan of Peter-Paul Koch's work for some years. He freely offers his work up for others to appaise, and is happy to share his knowledge. Now he's sharing some of his best tricks in printed form, and you too can become a Javascript expert. The book was released in Europe during October.
My copy is currently at my bedside, and is getting gently thumbed in the late hours. I'm pleased to say that it meets my expectations thoroughly. It is well written, concise, thoroughly cross referenced, and most of all authoratative.