If I know that non-mevushal wine is available to be used for avodah zarah (as in http://www.mechon-mamre.org/i/5211.htm) and that the prohibition against lifnei iver includes non-Jews, then am I forbidden to give a non-Jew a bottle of non-mevushal kosher wine as a gift, let alone a bottle of non-kosher wine?
This question and its answers indicates that avodah zarah, according to some, still exists as a problem.
 The prohibition of aiding the commission of a transgression is not one that belongs to the family of not harming another. After all, the other in this case is "harming" himself. Rather, by aiding in the commission of a transgression by another, one is to some extent becoming a partner in the sin. This naturally applies whether the other is Jewish or non-Jewish (See R. Elchanan Wasserman, Kovetz Shiurim, Pesachim 95; Responsa Arugat HaBosem YD 235). Source.