Also, from a recent interview with Sherman in the Seattle Times:
Q: And were the cartoons your idea?
A: Yeah. When I started writing it as a novel, for some reason in the first paragraph, I made [the main character] a cartoonist. I sent Ellen Forney, who is a friend of mine, about a page, I think, and I said, “Can you draw a cartoon of this?” About five minutes later, it came back over the e-mail. So she was a part of this five minutes into its creation.
I’m getting angry, though, because people are assuming I had nothing to do with the illustrations, that the press hired her. It was a really collaborative effort. Some of them I dictated, some of them we did together, some of them she did on her own.
I’m glad Sherman is noting that, because he and I did work together really intensely. (And, I did do a lot of it on my own!)