Newbery Medal winning author Lois Lowry's latest book in the Giver quartet is Son. Gathering Blue (2000) and Messenger (2004) were numbers two and three respectively. Son is the fourth. You might want to read the NYTimes Sunday Book Review article, "The Searcher" on Son.
What is most impressive is the author's life story about her own son, Grey. Read this fine NYTimes Magazine article "The Children's Author Who Actually Listens to Children" to learn more.