Millions of people already updated to IE9. Microsoft counts more than 2 million downloads on Day Zero, and much more since then.
It’s a great moment for the Web Design community. Although everybody here is using a better browser, most end users still use IE. And an update like this bringing HTML5 and CSS3 to the masses is a great moment. Developers using Linux or Mac don’t even need to test on IE9 every time, since every modern browser has the same features. No more doubled efforts to develop we had with IE6 ou 7.