It’s great that XMLHttpRequest is finally becoming an official standard. It’s better though, that the “other” browsers didn’t wait for this before implementing it. Real progress has happened as a result, in particular the recent popularity (& naming) of the AJAX technique, and the somewhat-related “Web 2.0″ phenomenon.
The news also makes me smile at the anti-Microsoft folks who have thrown stones at Internet Explorer’s standards support — once again the IE team innovated (*overused word through gritted teeth*) a proprietary extension, and it was such a good thing that the competition swiped the idea, thus making it a de-facto standard.
I’d rather have a good de-facto standard now, than an official one too-late. End result: Developers and Users win (and they already are winning).