Earlier quoted context omitted.
Also (from right now) it seems that Gruber doesn't know what browser sniffing is (or at least pretends to), but still has an opinion: http://daringfireball.net/linked/2010/06/04/html5-safari-ope...
What’s hard to understand about Apple’s pages? > The demos below show how Apple’s Safari web browser supports the capabilities of web standards such as HTML5, CSS3, and JavaScript. Gruber’s point is this: if Opera wants some better “HTML5” demos (presumably that work across browsers, and don’t just “use HTML5 as a buzzword”) they can easily make some themselves. Why should Apple be responsible for making sure their S…
Because the whole point of the exercise is to show how standards-compliant, open, web apps work so great on iPhone OS. Except by excluding every browser but Safari, it may as well be a front for the App Store. It might be standards-compliant, but it sure as heck isn't open or inclusive. In that regard, even Flash runs in more browsers than this showcase does.