There has been continued discussion [1] in other fora on the addition
of an element that identifies the main content of a web page, the idea
has been around for a long time.

This element would formalise common the common practice [2] of using
an id value such as "content" or "main" (typically on a div) to
identify a container element for the main content area of a document
or application. It would also provide an element that is a  HTML
version of the ARIA role=main.

I have put together a draft definition of such an element for
consideration and discussion:
http://www.html5accessibility.com/tests/maincontent.html


[1] http://lists.w3.org/Archives/Public/public-whatwg-archive/2012Sep/0008.html

>From publically reported studies  of id values used in HTML content,
the use of the strings "content" and "main" are common practice.
[2] http://triin.net/2006/06/12/CSS#figure-34,
http://westciv.typepad.com/dog_or_higher/2005/11/real_world_sema.html