From our
Kindle blog:
Amazon releases Kindle iPhone app
Kindle books can now be read on iPhones. Amazon has released an iPhone app which can read e-books from Amazon's Kindle Store - the first non-Kindle device with that capability.
This opens up the Kindle Store for purchases from people who may not have a Kindle.
And, for people who have both a Kindle and an iPhone, Amazon's WhisperSync feature keeps track of where you left off in a book as you switch between reading from your iPhone or your Kindle.
The Kindle for iPhone app is free and available for any iPhone or iPod Touch, with firmware 2.0 or higher.
From Amazon's FAQ page for Kindle for iPhone:
The entire selection of books available for reading on Amazon Kindle can also be read on Kindle for iPhone. You can also download free book samples from the Kindle store and read the first chapter of a book before you decide to buy.
Periodicals such as newspapers, magazines, and blogs, and personal documents cannot be viewed on Kindle for iPhone.
Some screenshots of the Kindle app: