For some reason, they've removed it in v4.
Gratz on the release
Also: I'm on Opera and get a lot of CSS errors. Some are strange: "-o-opacity is an unknown property".
I don't see plugins.js and main.js loading twice. And that CSS warning can only come from other tabs you had open as we don't include any `-o-` prefixed code in the CSS.
"Who uses HTML5 Boilerplate?
Google, Microsoft, NASA, Nike, Barack Obama, Mercedes-Benz, ITV News, BAE Systems, Creative Commons, Australia Post, Entertainment Weekly, Racing Green, and many more."
You can put any other frontend framework on top of H5BP - Bootstrap, Foundation, etc. It's not mutually exclusive.
Two websites using it: http://creativecommons.org/, http://www.barackobama.com/
One of the ways to know, before the new release which sadly kills it, was that many sites didn't customize the default hot pink text-selection background color.
Select text and get hot pink? You knew it was the boilerplate.
Will check out the updates shortly.