HTML 5 - when will it become standard, and what (if anything) should website designers be doing to prepare for it?

I very nearly de-railed a thread in the Website Reviews group when Dave Cooper posted up an excellent and thought-provoking post about learning HTML / XHTML / CSS in reply to a comment I made in there. Dave advised that "I wouldn't suggest anyone wastes time on XHTML now: development's been abandoned and HTML5 is going to be the next standard apparently, so you might as well use HTML4."

I was very interested and intrigued by Dave's comments, which prompted me to do a Google search for "HTML 5". I discovered some very interesting results, not least of all from W3C: http://www.w3schools.com/html5/html5_reference.asp .

I must admit that, to my embarrassment, I was only vaguely aware of HTML 5, and didn't realise that it was a potential successor not just to HTML 4, but to XHTML as well.

Rather than further de-rail Sheila's thread in Website Reviews, I thought I'd start this thread up to discuss HTML 5, it's potential impact on website design, when it's likely to come into force, and what (if anything) website designers should be doing to prepare for its arrival in terms of their own individual coding practices, etc. This is of particular interest to me, as I have only recently begun to expand my knowledge beyond "basic" HTML into the realms of XHTML and CSS, and so would very much like to know what impact HTML 5 could have in terms of where I should be focussing my attentions.

Many thanks once again to Dave for prompting me to research this, and I very much look forward to reading your replies! :)

Best wishes,

Chris