[dnquark]

This is a great project. There's no reason that any textbook, academic paper, or even a video lecture today shouldn't have a Medium-like comment/question/discussion layer. Academic papers are a natural place to start for obvious reasons (they don't undergo multiple editions once published, for example). Unfortunately, for-profit academic publishers (Elsevier et al.) have little incentive to introduce these innovations, and PLOS seems to have done little beyond allowing people to add comments at the end of an article.

Starting with famous out-of-copyright academic papers is a promising idea -- at the very least, we will hopefully end up with community-annotated versions of classic papers, which would be a great development in its own right. How long does copyright last on academic papers anyway?

Collaborative annotation has to be the future of academic publishing; the more projects push us in that direction, the better.