I'd appreciate if anyone can comment on the support the HTML+RDFa 1.1 draft currently enjoys.
I need to implement support for the Open Graph protocol to an existing HTML5 web application and wish to do so without introducing XHTML.
So, as far as I managed to figure out, this should be completely valid:
If I implemented RDFa in a non-XML document, would Facebook, Google and other services be able to parse the data correctly? I can't find the links right now, but there are some resources on the web that have suggested monkeypatching your Web applications to serve RDFa pages as XML to requests originating from Facebook, Google, etc., just to be on the safe side. Do you consider that to be a necessity at this moment?
Google doesn't currently read OGP data - it mostly just supports its own RDF vocabulary (see http://rdf.data-vocabulary.org/), though has rcently announced support for an ecommerce vocab, GoodRelations.
Anyway, Google and Facebook certainly support RDFa in non-X HTML.
By the way, OGP's namespace is now xmlns:og="http://ogp.me/ns#".
Edit 1, added: you should be aware that the W3C validator doesn't currently support HTML+RDFa, only XHTML+RDFa.