Just came across this:

Reinventing HTML by Tim Berners-Lee

I definitely suggest checking out the entire article because it outlines his plans for the future of HTML, XHML, and more. Some key points:

Some things are clearer with hindsight of several years. It is necessary to evolve HTML incrementally. The attempt to get the world to switch to XML, including quotes around attribute values and slashes in empty tags and namespaces all at once didn't work. The large HTML-generating public did not move, largely because the browsers didn't complain. Some large communities did shift and are enjoying the fruits of well-formed systems, but not all. It is important to maintain HTML incrementally, as well as continuing a transition to well-formed world, and developing more power in that world.

The plan is to charter a completely new HTML group. Unlike the previous one, this one will be chartered to do incremental improvements to HTML, as also in parallel xHTML. It will have a different chair and staff contact. It will work on HTML and xHTML together. We have strong support for this group, from many people we have talked to, including browser makers.

There will also be work on forms. This is a complex area, as existing HTML forms and XForms are both form languages ... A goal would be to have an HTML forms language which is a superset of the existing HTML language, and a subset of a XForms language wit added HTML compatibility ... There will be a new Forms group, and a common task force between it and the HTML group.

There is also a plan for a separate group to work on the XHTML2 work which the old "HTML working group" was working on. There will be no dependency of HTML work on the XHTML2 work.

I'd like [the HTML Validator] to check (even) more stuff, be (even) more helpful, and prioritize carefully its errors, warning and mild chidings. I'd like it to link to an explanations of why things should be a certain way.