This is such awesome news that I'm practically besides myself with joy. I think web app developers should make a concerted effort to push adoption of the Chrome Frame plugin, just like Adobe's flash player plugin.
I tried it today on an app that I'm working on which looks like hell on even modern versions of IE. Worked seamlessly.
I can see developers of wide-audience consumer facing sites still facing real resistance towards dropping support for IE6. However, corporate IT and web apps written for the "enterprise" should have little trouble getting this plugin adopted.
Put the following meta tag in your app to activate Chrome rendering on IE: