I have seen via several people on my FList, most especially julia_here, that Nan passed away yesterday afternoon. You can read the announcement here.
I remember meeting Nan at writercon in 2004. She was a very nice woman and we did talk sporatically through the whole conference. She occassionally dropped by this LJ to offer words of encouragement and give concrit to Water Hold Me Down. She was always very generous and her comments meant more to me than I can say.
I was looking forward to seeing her again in July so I could tell her face-to-face. I'm sorry that I now won't get that chance.
I didn't know Nan well, but my heart goes out to her friends and family, both online and off, for your loss.