score:3
I believe you have misremembered in this case.
LDS First Presidency letters to all members used to be available at http://www.ldschurchnews.com/letters, which now redirects to Deseret News. It seems http://www.ldschurchnewsarchive.com/letters has the former content of that site.
The First Presidency never issued a general statement on women giving or not giving the last address of a sacrament meeting.
FYI, two points about this tendency:
Another gender-based order (this time, in reverse) that is common in some places is for men to give the invocation, and women to give the benediction -- thus allowing women get the last last word ;)