I am glad to see this because it will encourage more web developers to add semantic markup. The last appendix in my new book (APress: "Intelligent Scripting for Web 3.0) briefly covers RDFa. In principle I prefer publishing separate RDF feeds but with support in Drupal for RDFa (and, I hope, other CMS systems like Plone) RDFa may become commonly used - a good thing if it happens.