The book is "A Muggle's Guide to the Wizarding World: Exploring the Harry Potter Universe" by ECW Press, author Fionna Boyle, AKA
The book was just released in Canada this past week, and it is available on amazon.com, but I'm not sure if it's going to be stocked in California bookstores. I will be keeping my eyes out for it...I will take a photo of it on the shelf if I do see it! ;)