Nimbus is cloud computing for science.

Nimbus Platform is an integrated set of tools that deliver the power and versatility of infrastructure clouds to scientific users. Nimbus Platform allows you to combine Nimbus, OpenStack, Amazon, and other clouds.
Nimbus Infrastructure is an open source EC2/S3-compatible Infrastructure-as-a-Service implementation specifically targeting features of interest to the scientific community such as support for proxy credentials, batch schedulers, best-effort allocations and others.