The artists are harking back to the retro 50's and 60's styles when illustrating these films and shorts.
Keep an eye out for Disney/Pixar's Presto and the upcoming film Bolt .
I've already found a copy of Bolt, and if the film actually had a visual style as the book, I might actually want to see it. Just my own personal opinion of all the similar looking CG films that Hollywood is pumping out.