For those of you who have been to my workshop this year, I have used as a good example of Photo Story 3 from Microsoft, a little book trailer about the book Sammy The Seal by Syd Hoff. I thought using Photo Story this way was a great idea so that children could get to talk about a book that they really liked, and practiced scripting and presenting a shortened version of their favorite parts. They also were engaging in persuasive writing as they tried to encourage others to read the book. I still think that the "child made" book trailers will make for the best learning experiences.
Today, while searching for Sammy The Seal example (the article was lost on the web) I came across an article written by the teacher who had first created it. Finding this, I discovered that there are many, many Book Trailers already done on Photo Story and, although your students would not be actually doing the presentation, they could watch and listen to these and maybe find some books that they would like to read. I think the collection, Book Trailers - Movies for Literacy is great for both ideas and examples. It also helped me refind Sammy The Seal.
I am sorry to say that for those who only use MAC - I have done the research and Photo Story is only available for the PC. You, of course, have IMovie and can do the Book Trailers...you just won't be able to use the ones that are collected here.