Also Thursday, Amazon said that it was working on making the titles for its popular e-book reader, the Kindle, available on a variety of mobile phones. The company, which is expected to unveil a new version of the Kindle next week, did not say when Kindle titles would be available on mobile phones.“We are excited to make Kindle books available on a range of mobile phones,” said Drew Herdener, a spokesman for Amazon. “We are working on that now.”