Bessie at Ancestral Ties headed an effort to add information about John Morgan's wives to his gravestone, since they are not all buried in the family plot. That project was finished several months ago, and here is her description. (John Morgan Gravestone Project completed.) Thank you, Bessie!
[Original post July 30, 2012. Update September 29, 2012—My mother found a photo she took of the newly completed gravestone during a recent visit to the Salt Lake City Cemetery and I have included it here. Many thanks to her for sending the photo!]