The Semantic Web Deployment Working Group and XHTML2 Working Group have published a Candidate Recommendation of RDFa in XHTML: Syntax and Processing. Web documents contain significant amounts of structured data, which is largely unavailable to tools and applications. When publishers can express this data more completely, and when tools can read it, a new world of user functionality becomes available, letting users transfer structured data between applications and web sites, and allowing browsing applications to improve the user experience. RDFa is a specification for attributes to be used with languages such as HTML and XHTML to express structured data. See the groups’ RDFa implementation report (although this document is still evolving as new implementations come in). The Working Groups also updated the companion document RDFa Primer.
A set of RDFa technology buttons have also been published, linked in from the Semantic Web logos’ index page.