Updated 5:25 a.m. PST Wednesday to note the official release of the Kindle application.
The program will be available for download for Apple's App Store and give users access to the more than 240,000 e-books that Kindle users can buy on Amazon. The program's Whisper Sync service promises to keep track of a reader's place in their chosen book, allowing users to pick up where they left off on either device the Kindle or iPhone if users own both.
While other e-book reader such as Stanza from Lexcycle and the eReader from Fictionwise are already popular on iPhones, it is the first time that Kindle content has been made available on a non-Kindle device. Amazon Vice President Ian Freed hinted at the move in an interview with CNET News last month, and expressed optimism that some of those who try Kindle on a cell phone will ultimately buy Amazon's device.
The app release is Amazon's latest salvo for a greater piece of the e-book market. The e-tailer unveiled the second generation of its Kindle e-book reader on February 9. Amazon touted the $359 Kindle 2 as thinner than its predecessor and offering longer battery life.
But the company quickly came under criticism from the Authors Guild, which claimed the device's new text-to-speech feature would hurt sales of audio books. The trade group representing 9,000 authors argued that Amazon wasn't compensating authors for the feature, and thus violating authors' copyrights. Amazon ultimately acquiesced, announcing late last month that it would modify systems to allow authors and publishers to decide whether to enable Kindle's text-to-speech function on a per-title basis.
In launching the new app, Amazon is taking on Google, which last month launched a mobile version of its Google Book Search, giving iPhone and Android users instant access to more than 1.5 million public domain books.