Learn the JavaScript language and browser/DOM programming first, then the actual HTML5 stuff is a few simple additions. Dive Into HTML5 seems pretty good.

* "JavaScript: The Good Parts" by Crockford

* "JavaScript: The Definitive Guide" by David Flanagan

* MDC's "A Re-introduction to JavaScript": https://developer.mozilla.org/en/A_re-introduction_to_JavaSc...

* Resig's "Learning Advanced JavaScript": http://ejohn.org/apps/learn/

* MDC: https://developer.mozilla.org/en-US/

* Crockford's website: http://javascript.crockford.com/

* YUI Theater (especially Crockford's JavaScript talks): http://developer.yahoo.com/yui/theater/