Amazon has released software called Kindle Convert that enables you to convert printed books into Kindle format, according to
this article.
Of course, you still have to go to the trouble of scanning your book, spread by spread or page by page, depending on the book size and your scanner. Way back in the late 90s I used to scan my books and use an OCR program to turn them into digital files that I could read on my Palm Pilot. It was laborious.
Still, for $19 I might try it out. I have a few old books I'd love to read on my devices for which no e-book exists.