Today at Mix, Microsoft made a case for Windows Phone that was a step up from vague promises about delayed updates, side loading hacks, and low sales numbers.  After starting his part of the keynote with an apology and an explanation for the still as yet ongoing NoDo update debacle, Corporate Vice President Joe Belfiore spent the rest of his keynote unveiling new developer features for Windows Phone, a firm, official date for Angry Birds (May 25th), and some pretty impressive demoes of IE9 for Mobile running on Windows Phones.

What’s most impressive about IE9, however, perhaps isn’t gpu acceleration, or the new UI that places the address bar at the bottom of the page (in either portrait or landscape, woohoo!), but the fact that IE9 is in fact the very same core running on a Windows Phone as on your desktop.

What this means, as Belfiore pointed out, is that the same markup will run the same way on both the phone and the desktop.  What it also means is that development of IE moving forward will take place on a single core for the phone, the desktop, and whatever other form factors where IE makes its presence known.

Tom Warren from WinRumors.com was able, from the comfort of his own home, to capture a bit of the keynote demoing IE9, running on the upcoming Mango update, in a “race” against Safari on the iPhone and an Android Nexus:

[youtube_video]Or3wvF9ts0I[/youtube_video]

You can see the entire keynote on the visitmix website.

While the tests appear to show IE9 for Mobile in the lead in terms of performance on phones, what may not be so apparent is that the re-architecture of IE, from the beginning, was designed to create not only a modern, standards compliant browser, but one that could power not only Windows desktops but Windows Phones on a single core platform.  Sometimes the stuff under the hood is the most impressive of all.