Just ran across an “interesting” definition of Nimbus:

“Client-side cloud-computing interface to Globus-enabled TeraPort cluster at U of C”

… in these slides: http://eucalyptus.cs.ucsb.edu/documents/eucalyptus-slides-wolski-cloud_expo_apr08.ppt

There is a Nimbus client (which can be replaced by an Amazon’s EC2 client), true. But most of Nimbus is server side software.

Teraport (and other Science Clouds) are not “globus enabled” but rather host the server-side components of Nimbus. Nimbus converts a set of hypervisors into what some will call an “IaaS cloud” or “open source EC2″ (Nimbus was released before EC2 but EC2 protocol support has been added due to customer demand).

The remote messaging modules (EC2 and a separate WS system) are hosted in a container that is based on Axis — some Globus Toolkit components also use that. This is a thin layer that provides marshalling/unmarshalling and security, converting messages to a common format for use with the framework independent “meat” of the Nimbus service (it could be hosted in another container).

See the FAQ, publications, and news if you would like to learn more about Nimbus.