A quibble with the footnote - the author has muddled the history about the WHATWG and W3C pretty badly. The W3C rejected the WHATWG's work initially in 2004; the WHATWG then created the HTML5 specification (largely by building on Web Apps 1.0 + Web Forms 2.0) as a browser-backed guerilla group outside the W3C. The W3C then adopted their work in 2006 (
http://dig.csail.mit.edu/breadcrumbs/node/166), and a fragile partnership with the WHATWG has been in place since. The W3C therefore deserves little credit for the HTML5 spec - they declared HTML dead in 1998 after all, tried to turn the web into XML (via XHTML), and then eventually came back to earth in 2006.
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Surely it's also not simply being pedantic to insist that things like CSS3 (!) and SVG don't get lumped into the "HTML5" catch-all. Pity the poor designer or developer just getting to grips with this stuff who has to figure out what someone means when they say "HTML5".
Nevertheless, as Mark Pilgrim said:
"HTML5 will continue to be popular, because anything popular will get labeled "HTML5"."
(http://diveintomark.org/archives/2011/01/09/dive-into-2010)