I don't mean to be rude, but could you expound upon this a bit? What was the feature, and why was supporting IE6 critical to moving forward with it? I'm not in

I don't mean to be rude, but could you expound upon this a bit? What was the feature, and why was supporting IE6 critical to moving forward with it? I'm not in any way arguing that IE6 isn't a PITA. I suppose its the "holding back" part of it that I don't understand.