The goal of the Contrail project is to design, implement, evaluate and promote an open source system in which resources that belong to different operators are integrated into a single homogeneous Federated Cloud that users can access seamlessly.
Contrail will vertically integrate an open-source distributed operating system for autonomous resource management in Infrastructure-as-a-Service environments, and high level services and runtime environments as foundations for Platform-as-a-Service.
Further details:
http://www.contrail-project.eu/