This document provides an overview of Bionimbus and the Open Cloud Consortium (OCC). Bionimbus is an open source cloud for biomedical research that provides services like elastic computing, databases, data transport and analysis pipelines. The OCC operates open clouds and develops standards to bridge private and public clouds. It runs an Open Cloud Testbed and is working to build an Open Science Data Cloud. The OCC aims to develop interoperable cloud architectures and operate infrastructure at data center scale to support open science.