This is reported by the New York Times here:
E-Books Outselling Hardbacks
I bought an iPad when they came out but was skeptical I would like reading long books electronically. I hate reading on computers. Turns out I like it a great deal. Just finished Atlas Shrugged, a long book if there ever was one. (Unrelated note: Atlas Shrugged, a book published 53 years ago, is #42 on Amazon).
I will miss bookstores. Libraries will hold on, I think, but not as places to go get books.