Amazon.com Inc. is announcing a new version of its Kindle e-book reader on Monday. And, in a sign that the electronic book is gaining clout in the publishing world, Amazon is also expected to say it has acquired a new work by best-selling novelist Stephen King that will be available exclusively, at least for a time, on Kindle.

Many publishers have long feared that Amazon would persuade a major author to write for its Kindle on an exclusive basis. Although retailers such as Barnes & Noble Inc. have long published their own...