Hi Jason - the best place to look for the available objects is in the WADL (Web Application Description Language).
The CUPI WADL is available on any Unity Connection system at the following URL:
https://<connection-server>/vmrest/application.wadl
The schema for the objects can be found here:
https://<connection-server>/vmrest/schema
More information on WADL is available here:
http://research.sun.com/techrep/2006/abstract-153.html ~ Matt