Update: As one might expect, this API restriction has also hit Pocketpedia; the app is now pulled as well (as of 7/17).
Sudden removal of an item from the App Store isn't unheard of; sometimes an app has a hidden bug or a content problem, and if Apple hasn't seen fit to take it off the store shelves then the developer can take matters into his, her or its own hands. Even applications that would seem to be wholly gratuitous and obvious ripoffs of other companies' IP might make it past the first round of Apple's scrutiny, only to be abruptly pulled under threat of litigation.
Apps that leverage content from websites and online services have another hurdle to clear: they may run afoul of trademark or licensing restrictions that prevent them from doing particular things with data from those third parties... things like, ferinstance, using that data on mobile devices.
This all brings us to Scenario D: the 'D' is for Delicious, and it's Delicious Monster's iPhone version of Library that's undergoing an unwelcome and rapid yanking from the App Store -- and believe it or not, Apple has nothing to do with it. Earlier today, Head Monster Wil Shipley announced that the iPhone app is on indefinite suspension and is no longer for sale; this is the consequence of a particular clause in the Amazon API terms and conditions. Part 4(e) of Amazon's agreement, which Shipley is a party to due to the desktop DL app's reliance on Amazon for book and DVD data, reads as follows:
(e) You will not, without our express prior written approval requested via this link , use any Product Advertising Content on or in connection with any site or application designed or intended for use with a mobile phone or other handheld device.Amazon gave D-M an ultimatum: pull the iPhone app, or lose the API access for the desktop version of Library. Despite Shipley's requests for a mobile device exception, the big A did not relent. It's not 100% clear why Amazon chose to enforce this clause now, nor why the company is not providing exceptions to developers. We have an email in to their press office to inquire.
If you've got DL on your iPhone already, enjoy. If not... it could be a long wait.
Anvil photo from flickr: fboyd and remixed via CC license.