If you're a retailer, you're not looking so much at the browser percentage, but rather at the revenue percentage, which is about 1.6% for us. Enough to care about. We don't optimize for IE6, but we do make sure the site functions on it.
Interestingly smartphone traffic and sales are approaching IE6 traffic levels and they will probably cross soon.
Developers need to forget about it. IE7 is the oldest MS browser our company will test for, unless we are specifically asked otherwise by a client, which will obviously cost more. Supporting old and broken software is not reasonable nor is it even necessary.
If a company can't be bothered to upgrade their systems to support standards which are now years old, my company won't be bothered to support them.
Interestingly smartphone traffic and sales are approaching IE6 traffic levels and they will probably cross soon.