Here's a really good blog about story in animation. The blogger is story artist Jenny Lerew, and she offers some interesting insight into the pre-production industry.
Her post on pitching: http://blackwingdiaries.blogspot.com/2006/02/on-story-pitching.html
Her post on story simplicity: http://blackwingdiaries.blogspot.com/2006/02/on-story-simplicity.html
Also, I found this little "manual" on storytelling. This is not specifically about animation, but it is still important and interesting to read, if you want to know how to really reach an audience.