The top levels with scope notes are now in the National Science Digital Library Metadata Registry.
According to its website, "The Metadata Registry provides services to developers and consumers of controlled vocabularies and is one of the first production deployments of the RDF-based Semantic Web Community's Simple Knowledge Organization System (SKOS)."
You can find OSC in the NSDL's sandbox. The top levels are listed under concepts while their scope notes are listed under each concept as a property.
By participating in the NSDL, we both publicize the project as well as ensure that OSC will have interoperability with other controlled vocabularies. It is important to continue to update the registry as we develop second levels, change scope notes, etc. If anyone would like to have access to edit the registry, just let me know.