"Following Google's announcement ending support for Internet Explorer 6, I find myself wondering whether we (Web developers) really need to continue providing support for IE6 and IE7..."
What a shame. It took a move by a large company like Google to get you to wonder about supporting IE 6, rather than reaching this conclusion through your own experience and common sense. Of course, this shame is also a blessing, as I'm hoping that it will get others like you to question the same, and hopefully companies will all follow suit.
In my town to satisfy a push for more cycle paths they simply painted a picture of a white cycle at the head of all the sidewalks . . . chaos and injury ensued. No back tracking though - just some back-slapping about implementing a 'green' transportation policy!
You were lucky. In my town, they painted a picture of a white cycle on the bus that was waiting to hit you. And they covered the bus in sharp spikes just in case you had the luxury of brakes.
A mathematician is a device for turning coffee into theorems. -- P. Erdos