Ars Technica reports: Recently, the iPhone application Mazo (which provides mobile access to all things Amazon) was rejected--not by Apple, but by the online retailer. The speculation about why ends today, with the release of Amazon's own iPhone/iPod touch application, unimaginatively named Amazon Mobile (iTunes Store link, free, only available in the US store).

This is somewhat unexpected, because Amazon has an excellent iPhone-optimized version of its website, so there is really very little need for a client-side application. Then again, although the iPhone-optimized amazon.com is no slouch, Amazon Mobile is fast--maybe even faster than the desktop version of amazon.com. If you have a lot of online holiday shopping to do, this is definitely the way to get it done quickly.

Aesthetically, the mobile web and app versions take different approaches: the web version puts all pertinent information in a single page and tends to require some scrolling. Additional information is loaded through 1990s-style blue underlined text links most of the time.

In the app, pages that require scrolling are a rarity. This means that it's often necessary to navigate to another page, but this happens using the iPhone interface paradigm with a little hook pointing to the right. Selecting such a "link" makes the new page move in from the right, pushing the existing page out to the left. Standard iPhone-style navigation is available at the bottom of the screen.

Apart from speed and design, Amazon Mobile has a third feature to offer: Amazon Remembers. This allows you to take a photo of an item you want to remember. The photo is stored both in the application and in Amazon's cloud. But the interesting part is that "we also use a community of real people to research your photo and try to match it to a similar product on Amazon.com."

So I took a photo of a book I just happened to have lying around, which was compressed and uploaded to Amazon (over WiFi) in a few seconds. I assumed the "community of real people" would get back to me past press time, but I was mistaken: within a minute, I got an e-mail from Amazon informing me that the "Amazon Remembers service has found a product similar to the photo you recently submitted," with a link to the book's product page. 

This feature has the potential to be a real game-changer for Amazon--and one that could inspire fear in the hearts of brick-and-mortar retailers everywhere. Amazon suggests that shoppers use it for price comparison while browsing the aisles of their local store, and if it catches on, will give Amazon another way to take steal slice of the retail pie from other merchants.

There are applications on other platforms that do something similar using the bar code--which doesn't work on the iPhone, because the camera isn't good enough to make out the bars. However, the code-to-product lookup is slow and error prone. So Amazon's solution to use a picture of the product may be a winner: even if the product can't be identified, you still have a photo of it to jog your memory, which will probably work better than a photo of a bar code.

So, interesting first try. It's a good thing Amazon Mobile doesn't have the dizzying array of links, navigation, options, categories, lists, and recommendations that the desktop web version has, but with just a log in/out option and a small selection of items from your wish list (these scroll sideways), the "home" page is a bit sparse. And if Steve Jobs is serious about competing on quality rather than locking stuff down, he should be a man and let Amazon sell downloadable MP3s from the app. Currently, you can only save them to your wish list. But if you're an iPhone/iPod touch owning Amazon customer, this app is a must-have for just the in-app package tracking.