I picked this up on the site of MusicaSacra Forum.
Gregorian Chant: General: Vesperale for Sundays and Feasts to be expected next week
A Vesperale is the book used for the singing of Vespers in Latin.
Furthermore, the Abbot of Solesmes (the abbey where these books are produced) recently had an audience with Pope Benedict.
So… it has only been decades in prep, right?
I am pretty sure that this project had been blocked in the Congregation for a long time because there was a bias against communal singing of the office in Latin. Now that there is a different regime in place, the project could move forward.
It will be interesting to compare what comes out to a Vesperale prepared in Rome some years ago by a private group.