Stéphane Corlosquet (aka scor) talks about the RDF Mapping API, which introduces RDFa to Drupal 7. He talks about some of the possible use cases as well as some of the sites that became interested in Drupal partly due to it's Semantic Web capabilities. He also talks a bit about the FOAF+SSL log-in authentication mechanism that he is working on for the Science Collaboration Framework (SCF).