This paper delineates the main characteristics of the Episciences platform, an environment for overlay peer-reviewing that complements existing publication repositories, designed by the Centre pour la Communication Scientifique directe (CCSD ) service unit. We describe the main characteristics of the platform and present the first experiment of launching two journals in the computer science domain onto it. Finally, we address a series of open questions related to the actual changes in editorial models (open submission, open peer- review, augmented publication) that such a platform is likely to raise, as well as some hints as to the underlying business model.