September 2012 Standards Update
September was a busy month for HTML5 as it relates to image descriptions. After four years of raging debate, arguments, threats and electronic hair pulling, the HTML5 co-chairs and the HTML5 accessibility task force are finally coming close to settling the matter of what to do with @longdesc. The latest proposal has @longdesc being put back into the full specification but the actual details of its behavior would be moved to an extension specification. An extension specification lives alongside the main spec but is not part of the main spec. It is focused on a single technology or piece of markup, and can usually be developed in a relatively brief time period. (WebVTT– http://dev.w3.org/html5/webvtt/ — is one example of an extension specification.) In this particular case the @longdesc extension spec would really only be in effect until its replacement is fully developed and released. As one of the co-chairs put it, the spec would need to be “one that doesn’t attempt to portray publishing software that produces markup including longdesc as non-conforming; nor does it attempt to portray user agent software that doesn’t natively implement longdesc as non-conforming.” At this time, there’s still talk of developing @longdesc’s replacement in ARIA (recall aria-describedat), but that activity has no timeline as of yet.
The HTML5 working group, co-chairs and accessibility task force are still working on details, but so far it looks like most members have bought into the extension-spec idea. Assuming it is approved, responsibility for developing the extension spec would be turned over to the task force with the expectation that it would be finished in time for inclusion in HTML5 by mid-2014. Ideally, this work would be carried out in tandem with development of @longdesc’s eventual replacement.
Also, a new schedule for HTML5 has been released, with the goal of bringing it to full recommendation status by the end of 2014. You can read the details at http://intertwingly.net/tmp/html5-2014-plan.html . People are already beginning to make plans for HTML5.1, which is tentatively due for release in 2016.