Sierra was a bit older than a toddler when we took her to a book signing at The Voracious Reader. She had Matthew Van Fleet's first book, "Dog," so we thought she would enjoy his latest, "Cat." And she did. But she didn't really understand this whole book signing thing. When we got home, she got a marker and finished "signing" every page of the new book and started on the older book before I realized what was happening.
Moral: Make sure the child understands why the author is writing in her book.