Once we are getting close to making a first preview release, we should attempt to merge as many as possible of our ontology modifications back upstream to NCO et al. Only strictly telepathy-specific stuff should remain in the Telepathy ontology. This will require discussion with the Nepomuk developers about what to upstream.
I talked to the Nepomuk developers at Akademy, and we now have a plan for how to do this. Just need to get a patch for NCO written and submitted.
Done (at least for now).