Terpene is a project mainly written in Ruby, it's free.
Client (Ruby and command-line) for Nacreon
A client library for interacting with the Nacreon PaaS (see https://github.com/pete/nacreon). It includes a command-line interface (currently limited) and a client. It is (hopefully) written in such a way that it should function well as a reference implementation for clients in other languages, although the Nacreon API is not guaranteed to be stable.
Terpene will be updated when Nacreon is; we're using it to develop.