Amazon is doing a great job to make sure that not only are they not represented in the mobile space, but that when they decide they want to be, it will have been so poisoned that no one will want to deal with them.
They can't access Amazon from any mobile devices directly, but they could make the app query their servers and call the Amazon API from there (and even caching the results). Am I wrong?
Yep, you are wrong. Delicious Monster didn't query directly from the iPhone, but it still violated the TOS because it used the data gathered by the desktop version on the iPhone. So the TOS states "No using data from Amazon on a mobile device".
The explanation given when they put this policy in effect 2 years ago was that they hadn't decided on what they wanted to do in the mobile space yet and they just wanted to make sure nobody moved ahead without them. It's been 2 years and this is still their policy, so they must really be struggling over whether they want people to be able to give them money from mobile devices. Even something like this, with using Amazon data, fosters a much more active and healthy market that Amazon benefits from. That kind of thing is intangible, though, and businesspeople can be stupendous boneheads when it comes to such things. They assume the market is always open and active, with people integrating media products into their lives, regardless of what happens. They're wrong, and Amazons business will hurt if they make it more difficult for people to read about products Amazon carries (even if Amazon is not mentioned at any point). If some other source steps up, the market will still be helped, but Amazon will be left out in the cold as far as the information they currently gather from usage of their API, so it will end up hurting them one way or another.
I always imagined that it might break an agreement between publishers and Amazon, if people could price compare easily in bookstores.
Obviously, B&N and Borders would likely be toast if you had an 'Amazon in Your Pocket' app that really worked.
If publishers pulled their books, then Amazon might have some problems!
As it is, Borders may already be toast, in which case, maybe Amazon will be in a better position.
This can't be it, because Amazon already has their OWN mobile app in the App Store. They're only preventing third parties from using API data on mobile devices.
Correct, and the app seems to actively encourage poaching business from brick-and-mortar retailers: you can submit a photo of a product, and within a minute or so, you'll have a working link to an Amazon product page. I use it often to wishlist books I find at the bookstore but don't want to buy right away.
Perhaps they want to make some exclusive deals with Apple in the future, and don't want to go through the hassle / bad publicity if they disable the Amazon API on mobile devices in the future ? Perhaps they have some plans with the Kindle and are afraid that having other mobile devices using the Amazon API will hurt those plans ?
What for? If your idea is to have an app that they can't "pin" on anyone in particular, you're missing the fact that you need an API key for access, and that can certainly be disabled.
