On 16 October 2008 the W3C announced XHTML+RDFa as a recommendation. IMO this is an important milestone in the process of implementing the Semantic Web. The Doctype/DTD is now cataloged and usable by the W3C Markup Validator. By way of example of the use of basic constructs and syntax, I have composed a validated XHTML+RDFa page -- just general information for those who might be interested in the development of the Semantic Web. James
I have read quite a bit about this, the problem with much of the information on RDFa is that it is not based on the current standards. The W3C documents are detailed and extensive. Most of the examples that websites use are just pasted in from the W3C website but aren't updated to the current standard. I am currently testing some RDFa pages. They make good google snippets.
Drupal 7 is reported to include RDFa. That would at least boost the number of people using or considering using RDFa.
The concepts are easy. There is lots of linked data out there. My favorite way of showing it is a regularly updated image http://richard.cyganiak.de/2007/10/lod/ of data sets. I think planning what and how to use this is a big hurdle for many small companies. You have to make a commitment to be a pioneer. I would start with a few hand coded pages maybe an "about me" page to better understand what this is about.