Similarly to the Kindle for PC app, the iPhone app will allow you to buy, download and read ebooks from the Kindle Store on your phone, and will link to any existing Kindle account.
This means that if you own a Kindle, you'll be able to synchronise your bookmarks and notes between the ereader and your phone, and also access a library of your previously purchases books via Amazon's servers.
However, you don't even have to have a Kindle ereader to download and use the app, which will also allow you to read the beginning of books for free before you buy, choose between six font sizes and read books in full colour.
The Kindle App is now up for grabs on the App Store for free, joining the Kindle for PC and the soon-to-be-released apps for Macs and BlackBerrys as well in spreading the Kindle's reach. Give it a go, and let us know what you reckon to it below.