Look at that, we tracked down Microsoft's Joe Marini here at MIX11. He's in charge of IE on Windows Phone and as a result, has the latest build of IE9 running on his phone.
He gave us a few mins of demonstration and that browser sure looks nice (see it kick other browser's butts here). No word on Silverlight/Flash yet for IE9 and same with plugins/addons, but at this point we'll be quite satisifed with just this base for our browsing needs. We also dig the "Metro styled" menus now--looks much better.