It's no standard because apple developers extended Webkit with some additional tags but noone else. That's what makes it so sad. Even more sad is that they misuse the words HTML, CSS3, JS and standard to convince you of the oh-so-open world of Apple. MS did that for years and every web developer pays for that today. But somehow now it's ok..
You don't see how having to install Safari for Apples vision of the internet is the same vision that MS had when building their crappy extensions to the standard?