In a characteristically terse email missive, Steve Jobs responded to one app developer , "We created subscriptions for publishing apps, not SaaS apps." But with apps like Readability --- or, for that matter, media streaming -- the line between content and service is a tad blurry.

Given a choice between equally priced alternatives, users will invariably go for the option with the least amount of friction, which is where the Apple in-apps purchase plan stands to win. Would you rather tap once to make a purchase or fire up your browser and hunt down the subscription link on the publisher's website? Yep, that's what I thought.

Thus, we return yet again to that old chestnut, the battle between open and closed systems. Open systems tend to be messy, chaotic, and unpredictable, but usually spread the wealth more evenly. Closed systems can be brutally efficient and reliable, but tend to concentrate wealth and power in the hands of a select few. That's the same in technology or politics.

History tends to favor open systems in the long run. And if Apple doesn't provide one, . My prediction: Apple will eventually back down, slightly -- certainly after more viable competitors to the iPad arrive, beginning with the Motorola Xoom some time next month -- except it won't be characterized as backing down so much as "clarifying" the rules.

Because when the mob is at the palace gates demanding entry, your options shrink in a hurry. Even Emperor Jobs realizes that.