The document provides information on Nimbus, an open-source toolkit that focuses on providing Infrastructure-as-a-Service capabilities to the scientific community. It enables resource providers to build private and community IaaS clouds, and users to use IaaS clouds. It also enables developers to extend, experiment, and customize IaaS. The document then discusses OpenNebula, an open-source project aimed at building the industry standard open source cloud computing tool to manage the complexity and heterogeneity of distributed data center infrastructures. It was designed with principles of openness, adaptability, interoperability, stability, and to prevent vendor lock-in.