I don't recall anyone mentioning Secure Graph on the mailing list, so here are some links.
http://securegraph.org/ - SecureGraph is an API to manipulate graphs, similar to Blueprints. Unlike Blueprints, every Secure graph method requires authorizations and visibilities. SecureGraph also supports multivalued properties as well as property metadata. https://www.youtube.com/watch?v=JMde_jFDM2M - Joe Ferner, Senior Software Engineer at Altamira, describes the creation and use of Secure Graph, https://github.com/altamiracorp/securegraph - source code for the project.
