After saying Birkat HaMazon with a cup of wine, the Shulchan Aruch rules in OC 190:3, that at least a cheekful of wine must be drunk. If this was at a zimmun and the leader of the zimmun does not want to drink, the Shulchan Aruch rules in OC 190:4 that he can pass off the cup to one of the participants to drink the required minimal amount.
At a meal I attended this past Shabbat a woman initially volunteered to drink the wine. (In the end, the leader took grape juice and drank it himself.) At the time, I reasoned that this would have been acceptable, as women joining a meal of 3 men are obligated in zimmun just like the men (Shulchan Aruch OC 199:7).
Does anyone have any sources that indicate one way or the other?