I'd have thought t'were obvious why it was offensive, cos it's always used in the context of a derogatory racist sentence. Think someone has already said that in this thread.
Edit : Damn interesting article, I remember the story too. Thing is, I personally have never heard the word used in a non racist sense, is it reclaimable ? Cos to me it never seemed to not have a negative connotation, and those who argue otherwise just seem to be being wilfully pedantic.