It all depends on how much work goes into supporting IE6. If the amount of time is substantial, personally I would consider dropping it. But even until the bitter end, that decision depends on your target audience and how much you want that group to be forced to make a choice: upgrade or leave your site.
That's for functionality. I think we're long past the stage where you should care whether or not IE6 gets the same exact _visual_ experience.
For us, it certainly does. Our product's success depends on it working "for everyone". If you invite your structural engineer to the project and they can't use Woobius, you'll revert back to email or some other method, and Woobius will have failed. Therefore, if 5.6% use IE6, given that those 5.6% include some of the largest engineering firms in the UK, we have to support IE6.
That's for functionality. I think we're long past the stage where you should care whether or not IE6 gets the same exact _visual_ experience.