There is a very interesting post about AJAX improvements on the IEBlog. Looking past all the improvements in cross domain communication, I am particularly pleased to see that they are actively following the HTML 5 work, and implementing new functionality in accordance with the current working draft.
Also nice to see that IE8 features are becoming a part of the HTML 5 drafts.
In short, with all the focus around alternate browsers and standard compliance, it’s good to see that the IE team is hard at work.