Although XHTML 2.0 isn't ready for general use yet, understanding how the changes will affect your writing and code will be key to a smooth transition. With full XForms integration, separation of content and function, and other features, XHTML 2.0 promises to revolutionize the Web when XHTML 2.0 arrives.
XHTML 2.0 Explained - Sections and Headings (Page 4 of 6 )
The old <h1> through <h6> tags are still in XHTML 2.0. However, there is a similar feature intended to replace them. Basically, one just defines a section and then has headings in the section. Something along these lines can be done:
<section> <h>Heading</h> <section> <h>First Point Heading</h> <p>Content</p> </section> <section> <h>Second Point Heading</h> <p>Content</p> </section> </section>
The point of all of this is to add a level of structure to the document. Everything is laid out simply and in a hierarchal manner. Search engines can get the information more easily, and non-visual web browsers can more easily let the blind user access the page more easily since they just have to look at the heading in the <h> tag.
The new <p> element
Unlike old versions of XHTML, in XHTML 2.0 the <p> element can contain block-level elements. (It still can't nest <p> elements, though.) What this means is that it is possible to put lists in a <p> element, tables, and all other sorts of elements. The <p> will be more of a "conceptual idea of a paragraph" according to W3C, the makers of XHTML.
Forget <hr />, introducing <separator />
Not nearly as big of a change as all the previous lists, but <hr /> has been replaced with <separator /> in order to more clearly state its purpose. It will place a separator (usually a horizontal line) in the document.