Steve Jobs has reportedly weighed in on the iOS in-app subscriptions controversy with one of his famously terse e-mails, but the latest one-liner from Apple's CEO doesn't clear things up. Responding to an iOS developer's inquiry, Jobs purportedly said apps such as Dropbox, Evernote, Salesforce and other similar software-as-a-service (SaaS) apps would not be required to use Apple's new in-app subscription service, according to MacRumors.

"We created subscriptions for publishing apps, not SaaS apps," Jobs reportedly said in the e-mail. Jobs' note comes soon after Readability -- an online service that allows you to save the text of articles for later reading offline -- complained in a blog post that Apple rejected its iOS app for failing to use the new in-app subscription service. Readability charges a recurring membership fee for its service and then distributes 70 percent of its profits to writers.

What is SaaS?

Apple appears to be drawing a distinct line between apps that deliver content to iOS users such as Rhapsody, Netflix or The New York Times, versus services that offer online document storage, note-taking services, business tools and other subscription-based software tools.

The thin digital line

The problem is that the line Apple draws between SaaS and content publishers may not be so clear. For starters, is Readability a SaaS or a publisher? It's true that Readability offers you news content, but is it publishing that content? Not really. There's little difference between bookmarking this article you're reading right now to access later using Readability or Instapaper or just highlighting the text, copying it into a text file and stashing it in Dropbox. Yes, the Dropbox method is a lot more work, but the end result is the same: a set of text articles set aside to read later. What's the difference? It would seem Apple believes one method is content publishing (Readability) and one is SaaS (Dropbox).

Are things really as they seem?

But there is one important thing to find out: Was Readability rejected for implementing an alternative to Apple's in-app purchase system or for not using the company's system at all?

Readability said in its blog post that it was rejected for violating section 11.2 of Apple's App Store Review Guidelines, which reads, "Apps utilizing a system other than the In App Purchase API (IAP) to purchase content, functionality, or services in an app will be rejected."

That guideline says nothing specific about in-app subscriptions (although it does mention "services"), but dings apps for using payments systems other than Apple's. A few lines down, Apple deals with subscriptions in section 11.11 saying, "Apps offering subscriptions must do so using IAP..."

But Readability wasn't rejected for section 11.11, according to its blog post; it was rejected for section 11.2. That's a significant difference, and it's not clear what's going on. If Readability was penalized for not implementing a payment system at all then you can easily complain about Apple's policies.

But if Apple just said, "Sorry, you can't use your own in-app payment system in your app, you must use Apple's," is it really that bad? Couldn't Readability just implement their app without a payment system, and allow existing members to sign in and pay outside of the app? Perhaps it couldn't since Apple has said that apps offering subscriptions must do so inside the app in addition to the service's own Website. But it's not really clear what's going on here or where Apple's problem with Readability lies. I have dropped Readability a note and will update this post should Readability respond.