Semantically Interlinked Online Communities Ontology known as SIOC is now officially under the W3C, for example it now has a stable version hosted on the W3C website. From the summary of the presentation:
SIOC (Semantically-Interlinked Online Communities) Core Ontology provides basic concepts and conditions for describing information from online communities (for example, forums, wikis, blogs, etc.) on the Semantic Web. This document contains a detailed description of the SIOC Core Ontology.
The development involved in DERI Galway, DFKI, FhG-FZI, CTIC, OpenLink Software Inc., Opera Software, STFC, UPM, and the University of Trento.