I found this book at a second hand shop on the weekend. 2006, 200 pages, 12x7".
There used to be a blog out of which the book sprung, but it's now sadly defunct.
Lots of awesome art by the heavy hitters of 50's cartoons: Maurice Noble, Tom Oreb, Eyvind Earle, the amazing Mary Blair and a score of others.
It's gorgeous; basically a history of mid century american animation; UPA, Disney, MGM, Warner Bros, Hanna-Barbera, etc. Every page is full of hi-res color scans of cels, concept art, color keys, and mad textual info.
You can order it from Amazon for $30.