The result of tons of work by lots of smart people. Go forth and implement. And I need to put in a plug for Metadata for Grandma which (indirectly, as it turned out) influenced the spec. RDFa is already a big deal, used in places like SearchMonkey. The subset of RDFa used by SearchMonkey is 100% conforming to the CR.
I’ll have more thoughts and perhaps implementation notes on this later. -m