Glad to see two big dogs from 37Signals calling for this a day apart from each other. www.pen.fm is actually moving straight into this direction as a platform to allow self-publishing of all sorts of mediums. Super-clean and perfect conversion is a hassle, but if we can track/mark each component to begin, everything regarding styles and rendering becomes so much easier to control. Currently we're on stories and going into manuals, but I can see magazines being the next hit. :)