Redmond has been sleeping, no doubt. But that is neither here nor there. It's refreshing to see other browser teams giving the IE team a run for their money and whipping them into shape -- they've been needing that for almost 10 years, finally getting them off their laurels. Competition is the best part of the space, and that should include innovative APIs (not yet standard) that us engineers can exploit to make our applications better, faster, or stronger. I'm certainly not going to wait for some standards committee to deliberate for 8 years over some monolithic spec that every browser will get wrong anyhow, as history has shown.
http://en.wikipedia.org/wiki/XMLHttpRequest#History_and_supp...
You'll note the browsers implemented it before standardisation, as is traditional and sensible despite Microsoft's fervent myth-making to the contrary.
(I note that you now seem to be claiming that IE was simply resting on its laurels in a turtle vs hare fashion, rather than being forced into retirement by over-regulation)
Please don't mindlessly repeat Microsoft's line about having to wait for standards to be signed, sealed, and delivered. It's just spin. They have a broken development model (and a financial interest in holding back the web) and that is no-one's fault but their own.