After all, Google still happily sells clicks to IE 6 users. If you're business relies on external ads and optimizing conversion rates, IE 6 remains a priority.
For search results it's probably more worthwhile and not as hard to support the IE's but for their other apps they say they are only supporting that two most recent browsers.
I would actually argue that Google Search is still supporting IE6, just as a degraded experience. Dropping support all-together means they just ignore it exists, which is far from the truth and likely won't happen for 5+ years.
And, yes, I can give a few examples were the webdevs ignored legacy browser support and got burned.
But just last week, another subcontractor apparently didn't realize that our government client was stuck on Flash v9 and spent the next two weeks trying to sort it out.
And it hasn't happened in a few months, but we used to get occasional complaints from clients stuck on Safari v4.