Cloud computing represents an opportunity for a powerful convergence in which the societal investment in massive HPC systems can be brought to bare in a general purpose fashion. Cloud computing provides arbitrary consumers on-demand access to the aggregate computational power of data-center scale systems with compelling economic advantages. These clouds will increasingly adopt the kind of highly integrated and balanced systems pioneered by and used in HPC. Reflexively, cloud economics and the potential for broad utility and amortization can help foster the development and deployment of extreme scale systems. In this talk we describe two aspects of our work in exploring this convergence. In the first part we describe the Massachusetts Open Cloud (MOC), a new "open cloud" concept targeting big data and HPC applications. In the second part of the talk we describe our work on a new system software architecture and runtime that targets the challenges associated with developing software that can efficiently leveraging such systems for a broad spectrum of applications and use cases. We describe this system software effort in the context of the lessons from our past systems research.