All I can say is, wow...
I guess I shouldn't be surprised though, as tracking is part of their business model.
And of course, if Yahoo is going to do it, I also wouldn't be surprised if others start doing it as well, making DNT useless.
It's interesting though that they're not taking into consideration, the fact that many of their users
may want DNT to be on! And if they do, it can't be done by a simple browser preference.
They've basically thrown down the gauntlet and said, "If you don't want us to track you, you'll need to use our tools to do it..." :s