[hoppipolla]

Technically there is still only one "HTML5" standard; the W3C one.

WHATWG are editing the "HTML Living Standard". Unlike the W3C model, there aren't version numbers or set phases that the spec must go through. Instead there is a process of continuous development; fixing bugs as they are found and continually iterating new features in response to the evolving needs of the web. This process is modeled around the way that browsers are actually developed, and should help innovation on the web keep pace with proprietary platforms.

The goal of the W3C version is somewhat different; it is essentially a branch aimed at stabilisation (likely at the expense of accuracy) in order that there is a well defined set of technologies covered by the W3C Patent Policy. It is also governed by a somewhat different (consensus based) decision making policy compared to the WHATWG version (the editor specs what people are willing to implement). History suggests that any differences that arise are most likely to be in things that don't affect UA interoperability but concern the definition of a valid document.

So the net effect of this change is that we will once again have a version of the HTML spec being developed using the system (and at the speed) that gave us HTML5 in the first place.