Sisters giving the concluding talk in a sacrament meeting, where did my source go? Broad context: I have seen at least one question on this site asking about the customs in LDS meetings regarding women, and this question sometimes comes up offline as well. I think I remember, not too long ago (2013 or 2014), I read or heard official communication reminding/ stating that there is no objection to women giving concluding talks in a sacrament meeting (I am certain the notion that priesthood holders should have "the last word" in a meeting didn't just creep in in my ward).

But when looking for that communication on lds.org, I didn't find it. I thought it was a letter from the First Presidency, but I think I would have found that. I didn't find it in the handbook either. Did something like this get mentioned in a world-wide leadership training or the General Conference? Does anyone know what I am looking for, or does my memory fail me here?
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: 


It is highly customary for talks from visiting authorities such as High Councilors or Stake Presidents to come at the end of a meeting. These are always men.
For the rest of the of the time, as you pointed out, it is most common for men to give the last address, though there's no policy for or against this. There's no real reason other than habit.


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 ;)