Amazon yesterday released a “Kindle for iPhone” app that lets users download Kindle books from Amazons vast library and then transfer them to either their iPhone or iPod Touch.

According to the app description, interested users won’t be able to peruse Amazon’s large e-book and newspaper catalog from within iTunes, but will instead have to go to http://www.amazon.com/kindlestore in order to browse around. Once a user finds a title of interest, they can choose to either wirelessly send a free excerpt of the book to their iPhone or instead purchase the product entirely and wirelessly transmit it to their iPhone.

Requiring users to use the Amazon website to browse for books might seem like an annoyance and an extra un-necessary step, but it actually makes a lot of sense.

Browsing through the iTunes App Store just for games, for example, can be exhausting and confusing, and there are only a few thousand titles to sift through. In contrast, Amazon has an assortment of over 240,000 Kindle ready e-books, magazines, and newspapers. Just imagine trying to navigate your way around that mess on iTunes. Moreover, Amazon’s website already contains a rich repository of book reviews, whose sheer length and volume make the decision to navigate through Amazon’s library via their website a logical one. And lastly, it’s Amazon’s app, so they can do whatever they want!

One of the cooler features of the app is that it allows users who own both a Kindle and an iPhone to easily switch between both devices while keeping the most current page synchronized between each device. Now that’s slick.

We haven’t yet given the new app a test run, but if the wireless transfer between Amazon’s website and the iPhone is easy (and early reports seem to indicate as such), then this definitely has the potential to be a killer app.

The app is free and can be downloaded from iTunes over here.