Google Search Engine Adds Support for RDFa, Or Do They?

Via a post and an interview on the O’Reilly Radar blog, Google announced limited support for parsing RDFa statements and microformat properties in web page HTML coding and using those statements to enhance the relevance of search results as so-called “rich snippets”. In looking at the example review markup outlined in the O’Reilly post, though, I was struck by some unusual and unexpected markup. Specifically, that the namespace was this http://rdf.data-vocabulary.org/ thing that I had never seen before, and the “rating” property didn’t have any corresponding range that would make that numeric value useful in a computational sense.