Black people can use the word. We can't. It's incendiary. That viewpoint is indefensible. The only thing cruder than racism itself is selective application of standards. I know proud African-Americans who would set you straight in a heartbeat on this.
When I lived in Atlanta I worked with an African-American woman who (when the manager wasn't around) used the n-bomb in a disparaging way to describe herself. When I told her what kind of damage she was doing, she replied, "when your people are beaten for hundreds of years like we've been, then you can have your own word - that word is OURS". I'll tell you the same thing I told her - this idea that the term has different meaning and different "rights" is a complete load of crap.