"Political Correctness" emerged as a term somewhere in the late 80's - what I believe it was intended to define was, as Bill Maher once described it, "the elevation of sensitivity over truth".
So, in my book - say, attempting to describe a person, but going to great lengths not to mention their ethnic background, for example, "well, he's tall, he's got short curly hair, a narrow nose", instead of "the black guy over there with the green T-shirt and the afro". This might be an example of political correctness.
Another, more serious example might be the reluctance to fund medical research that applies to differences medically between African-Americans and caucasions - there are people that believe that these issues should not be a part of medical research, because it focusses on differences between races. I'd also categorize this as political correctness.
However, I don't believe that not allowing bigotry is political correctness. Because it doesn't elevate sensitivity over truth. Considering racial epithets or slurs as unacceptable in ordinary discourse is a valuable protection for people against racial vilification - and these kinds of deliberately perjorative terms aren't actually "truth" anyway..
Its seems though, that political correctness has become a very broad term that describes different things to different people. What are people's opinions on political correctness?