iCloud is seamlessly integrated into your apps, so you can access your content on all your devices.
This is Apple's definition for the iCloud service. It doesn't matter what the data is, it's your data and Apple is promising to sync it between your devices, to preserve your experience.
In the case of Instapaper, the solution is obvious: Put the files in Documents. That is Instapaper's content and part of the experience that users want synced between devices.
If Apple penalizes developers and undermines the promise it is making to users because it decides to be miserly about bandwidth, then it has to admit it launched iCloud before it was ready.
Their marketing is definitely hyperbolic. Even in terms of Apple's own services. The supposed data syncing in iWork actually doesn't work on the Mac versions. It only works between iOS devices. So if I edit a paper on my Mac, and I want to use it on my iPad, I still have to go through an annoying uploading/downloading phase. There's nothing seamless about it.
I know this is a tangent to the OP but I was very annoyed to discover this last night, I feel like Apple was pretty misleading here. There are clearly technical difficulties that still need to be surmounted.
"If Apple penalizes developers and undermines the promise it is making to users because it decides to be miserly about bandwidth, then it has to admit it launched iCloud before it was ready."
That's the key right there. The size of the Instapaper database is determined by the user. It will only fill up a user's iCloud space if they decide to save a lot of documents. Plus, they always have the option to buy additional space!
Aside from making sure the documents are reasonably compressed, the size of the Instapaper database should not be Marco's concern.
But it's not clear that Instapaper is allowed to put the files in Documents. According to the Data Storage Guidelines cited in the article:
1. Only documents and other data that is user-generated, or that cannot otherwise be recreated by your application, should be stored in the <Application_Home>/Documents directory and will be automatically backed up by iCloud.
2. Data that can be downloaded again or regenerated should be stored in the <Application_Home>/Library/Caches directory. Examples of files you should put in the Caches directory include database cache files and downloadable content, such as that used by magazine, newspaper, and map applications.
I don't know if this is something enforced in the approval process, but it seems like Apple's intention is for redownloadable content to all be stored in temporary, wipeable locations.
Still, when user saves a webpage to Instapaper he/she probably wants to see it as it was when it was saved, and not magically updating itself afterwards. So I think that 'exactly this article at exactly this point in time' should qualify as 'content that cannot be recreated'.
That is the title of Apple's main iCloud page at http://www.apple.com/icloud/.
iCloud is seamlessly integrated into your apps, so you can access your content on all your devices.
This is Apple's definition for the iCloud service. It doesn't matter what the data is, it's your data and Apple is promising to sync it between your devices, to preserve your experience.
In the case of Instapaper, the solution is obvious: Put the files in Documents. That is Instapaper's content and part of the experience that users want synced between devices.
If Apple penalizes developers and undermines the promise it is making to users because it decides to be miserly about bandwidth, then it has to admit it launched iCloud before it was ready.