I also have this question. On reading through the literature I have gathered that norfluoxetine is the demethylated form of fluoxtine and the reactive metabolite. From what I can gather, you take fluoxetine into your body, and it has a methyl (CH3) group cleaved from the amino group to yield norfluoxetine:
http://pages.cs.wisc.edu/~caitlin/papers/Prozac/
However, also listed is fluoxetine HCl, which i assume is the actual form fluoxetine is produced in pharmaceutically, with the HCl stabilizing the amino group of fluoxetine.