For us, there is no stigma attached to non-blacks using the word. The problem is intent. Like any word, it can be used negatively or positively, and I prefer not to have to second guess whether you meant it one way or another. So I kindly ask people, that I don't know well, to refrain from using it around me.
One night I was having dinner with my ex-girlfriend, who was full-blooded Italian, and her family. Her mother absolutely loved me. Somehow we got around to the topic of how much better I was than her ex-boyfriend, and her mom blurted out, "He was such a n-er." When she realized what she said, she looked at me and said, "But you're not a n-er. You know...there's just certain people that are." I never directly responded, and I wasn't sure how I felt about it at the time. But it opened my eyes to the complexity of even attempting to define what the word means to different groups of people.