It's live now for download.
I mean we heard about it when Amazon launched Kindle 2 but no one really thought it was going to happen this quickly. Least of all, Kindle materials would be coming to the iPhone/iPod Touch before G1 or other smartphones.
You can go directly here if you have iTunes installed. I downloaded a couple of free books and bought a Star Trek novel. So far I can say that it works as advertised. You can buy the books directly through Safari on the iPhone. It was quick and easy.
Once you open up Kindle for iPhone, the app automatically sync via Whispersync. You're taken directly to the "Home" page and you will see everything in your library. Simple.
Just as everyone is saying Kindle 2 is a great improvement over Kindle, I am waiting for Kindle For iPhone 2.0 or at least some sort of improvement over the UI.
After trying out eReader and Stanza, I suggest Amazon take a look at those two apps and see how far they've come on the iPhone. In fact, eReader has years of experience developing mobile ereader applications for the PC, Windows Mobile, and Palm.
Regardless, this an encouraging first step for Amazon as well as Apple. I'm certain Kindle apps for other platforms should be available in no time.