Say what you like about Microsoft, but these days they seem as committed to web standards as any other big organisation. Next to Google (who are lurching from one privacy fiasco to another) and Apple (who despite their tens of billions of dollars don’t have a single full-time web standards person), Microsoft looks like the good guy for once.
Despite this, and the huge strides they’ve made with Internet Explorer, I’ve always felt that IE9 prioritised CSS3 stuff over HTML5 stuff in order to please web designers. Specifically, things like border-radius and box-shadow were in, but the whole Web Forms 2.0 section was out.
Those important new input types and attributes have now been added to IE10, along with many HTML5 APIs such as Web Sockets and History plus a ton of other stuff. Sadly, IE10 will probably also support some -webkit-prefixed CSS properties.
Nobody’s perfect.