At risk of starting a flamewar, I'm starting to like Microsoft more and more these days. They have a 100% predictable support lifecycle and don't pull the rug out from under people with virtually no notice.
We've literally just got rid of our IE6 support a couple of months back and have IE8 as minimum spec (IE7 is irrelevant as any platform that can run it can take IE8). I doubt we'll see the end of IE8 for a few years which is not a problem for us.
And yet you can't install IE9 on Windows XP. You have to wonder why Google should go through the trouble to support users that even Microsoft won't support.
Finally, this is not an example of Google pulling "the rug out from under people with virtually no notice." This policy has been in place for over 18 months. I know some of you love to find things to hate on Google for, but this is not one of those times.
We've literally just got rid of our IE6 support a couple of months back and have IE8 as minimum spec (IE7 is irrelevant as any platform that can run it can take IE8). I doubt we'll see the end of IE8 for a few years which is not a problem for us.