on this page of the html5 spec
http://www.w3.org/TR/html5/scripting-1.html#the-script-element, you can find this text:
When used to include dynamic scripts, the scripts may either be embedded inline or may be imported from an external file using the src attribute. If the language is not that described by "text/javascript", then the type attribute must be present, as described below. Whatever language is used, the contents of the script element must conform with the requirements of that language's specification.
what that means is if the script tag contains a document that is NOT "text/javascript", then the type attribute is required. doesn't that imply that if it IS "text/javascript", the type attribute is optional?
Edit:
Also, if you paste the code from that example into the w3c validator at
http://validator.w3.org it will validate successfully as HTML5. It does have two warnings; one states that html5 is experimental, and the other is a warning about the direct input validator, neither of which have anything to do with the validity of the html in question.
A better argument may be whether or not the examples should be using html5 or html 4.01
-- Kevin