After several months of back and forth over whether to fully support RDFa in HTML5, Ian Hickson has posted his proposal for a generic approach to microdata in HTML5 (microdata being a catch all phrase covering the sort of things marked up in RDFa and Microformats). It uses a subset of the RDFa attributes and avoids some contentious issues such as namespaces and CURIEs. There has been some effort to ensure the HTML5 solution doesn't clash with RDFa (though perhaps not too successfully), however it's also not required to be compatible. Ian has asked for feedback, so if you have an opinion now is the time.
If you want to play around with the proposal there are already a couple of nascent parsers available: from Philip Taylor and James Graham.