As someone who gets excited by software, I love reading the change notes for each release. Changelogs aren’t just for software, though. Anything digital can benefit from one. It may be no surprise that I maintain a changelog for this site and for Build Your OmniFocus Workflow.
Though the changelog for this site is really just for me, in the case of the book, it’s quite important. Readers want to know they’ve both got the latest edition of the book as well as what to look for should there be any new content.