Hello, world!
My name is David McCabe, and this summer I am adding RDFa support to Semantic MediaWiki, as part of the Google Summer of Code 2008. I am an undergraduate in Mathematics at Portland State University. For the Google Summer of Code 2006, I wrote Liquid Threads, a MediaWiki extension that replaces talk pages with a threaded discussion system.
Semantic MediaWiki (SMW) is the software used for the CC wiki and many other wikis. SMW allows authors to mark up wiki pages so that their contents and relationships are machine-readable. SMW already publishes this machine-readable data in RDF/XML format.
You can read about RDFA on the CC Wiki. There is also a Google Tech Talk on RDFa.