HTML Canvas 2D Context was only one of the spun-off HTML5 drafts published today; HTML Microdata is another. this was previously part of HTML5 itself (section 5 in the last published HTML5 draft), and it caused quite a bit of controversy because its functionality overlaps almost perfectly with RDFa, but it uses an incompatible approach.
the Working Group Decision on ISSUE-76 Microdata/RDFa is an interesting read to get a feel for the tension between something that's more accessibly designed and less optimized for people with an RDF toolset, and the fact that RDFa already has seen some adoption, while microdata is a new approach.
regardless of how this will play out (ironically, a new version of HTML+RDFa was published in the same batch of documents as the new microformats draft), the
HTML Microdata draft is yet another addition to the HTML5 API Overview, which now has been updated.