From MIX '10 comes some Internet Explorer 9 Platform Preview Info. Short story: HTML5, hardware acceleration, and a public download that's appears to be available (Vista SP2 + only).
Personally I don't care about the IE9 rendering engine that much, even if it's faster than chrome/webkit/mozilla by a factor or 10x. What has put me off IE again and again is the user interface that sits around the rendering engine. The feel of it is sluggish and feels just.... "bleah". The big long list of icons to the right of the tabs, the menu bar sitting in the middle, the weird button/dropdowns for things like suggested sites, the little icon that pops up every time I select something and the huge long context menus.... Yech! I'm sure some of these things can be turned off, but honestly I don't get far enough to even bother, cause I just use IE to download firefox/chrome.
However for you fine readers, I'll take a bullet and am installing it on my home machine and will give it a run and report back. Who knows, maybe MS has taken the Windows 7 and Zune approach and hit one out of the park this time?
Update: OK, so the download is a tech preview, of no use to "normal" users as it is basically a rendering window with no UI. Only 55/100 on the ACID3 test, and the one quick test of the HTML5 site I tried (this canvas experiment) failed. The YouTube HTML5 site also doesn't work, but that could be a browser detection issue. Still, I have hopes that the speed/html5/css3 demos that they are showing off turn out being real in the end. Bringing these new technologies (blah blah not an official standard yet blah blah) to the browser that still (somehow) has 70%+ of the market (or whatever it is these days) is a Good Thing.