pageoneresults - 5:28 pm on Jun 3, 2011 (gmt 0)

I'd say they rushed things a bit. The W3 Microdata Specification is still a Working Draft as of May 25, 2011...

HTML Microdata
[W3.org...]

Now, let's talk about that [Schema.org...] website. I find it difficult to take anything seriously from an org who releases an HTML5 specification under an XHTML DOCTYPE. The site fails validation with a list of simple amateur errors. I don't understand why that site isn't using an HTML5 DOCTYPE?

The Microdata syntax will not validate when using anything other than an HTML5 DOCTYPE. So, for those of you who maintain valid XHTML code, this will present challenges. You may be forced to switch to an HTML5 DOCTYPE so that you can take full advantage of all things HTML5 and maintain valid documents.

Microdata is an extension to HTML5 that provides another way to embed Microformats and Poshformats vocabularies.

For common semantics on the web (e.g. people+organizations, events, reviews, syndicated content), microformats are still simpler and easier than microdata, and are already well implemented across numerous tools and services.

Microformats - Microdata
[Microformats.org...]