Where is the accessibility line?

Accessibility is constantly a main point it seems in web design – rightly so really when you think about it. A article by Clagnut highlights one area a lot of web designers (me too included often) do not consider, colour blindness. It makes you realise how in this age of web standards and accessibility we get caught up in only a small percentage we should be really considering. The question is where should the line be drawn really. Makes me recall the blah% don’t use flash and blah% use 800 by 600 to view web sites on their acorn electrons. Where the line is drawn really is a point for debate. So where do you think the line should be drawn?