Project Awesome is an HTTP proxy which means it's even a higher abstraction than a Ruby library :)

In any case, you should have a look at Libcloud (http://libcloud.apache.org/), jclouds (http://jclouds.org), deltacloud (http://deltacloud.apache.org/) and other libraries. Deltacloud exposes a similar functionality through an HTTP interface. We have recently also started working on "Libcloud REST" which will expose all the Libcloud functionality through an HTTP interface which means you will be able to talk to it through an arbitrary language which can speak HTTP.