And this is why competition is so important - look what happens at Microsoft when there's serious competition to IE
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From what I've read so far, it looks like Microsoft is pushing hard on performance and standards compliance on this one. Although I think Firefox is working on hardware acceleration and HTML 5 as well, it's nice to see that Microsoft is finally trying to push forward and actually try to make progress in areas people care about.
What I think has flown under the radars of a lot of people is how much they are actually doing with HTML 5. In fact, if everything I've read is correct, they are actually working a lot with the W3C to refine the spec and are helping the W3C write test for it.
In fact, they're doing so much, you might say that Microsoft is writing the new HTML specification. Okay, maybe that's going a bit too far - but it does seem that Microsoft has really changed their approach to how they deal with the whole issue of them lagging behind other browsers when it comes to specifications for web standards.
I'm undecided if this is a good or bad thing. However, this is Microsoft's new claim for compatibility with standards:

Source: IEBlog
That's right - Microsoft is, for the most part, claiming that IE9 is gonna beat the pants off of Firefox, Opera, Safari, and Chrome when it comes to standards support. Now, they're not really saying it explicitly, but they have been pushing forward a lot of tests for standards support, and they're mentioning the tests a lot in their blogs.
Problem is, they haven't really shown any UI yet, so there's no telling what it'll look like.
However, Microsoft's testing is to be believed, Firefox, Opera, Safari, and Chrome may end up in a role reversal when it comes to standards support.