movieos: "I'd buy a magazine in digital form if it came bundled as an Instapaper-powered list of articles, each of which tracked if I'd read them, and how far down I'd scrolled, synchronized this state with all my other iOS devices, and had associated images cached locally, and offered convenient 'tweet this article' functionality."

It makes sense to have different interfaces for consuming different types of content, I'm not suggesting this should be done in a typical feed reader. But no reason feed readers shouldn't implement these features.