Thanks to one of our readers for pointing out the following exhibition at The Getty Musuem in Los Angeles: Music for the Masses: Illuminated Choir Books.
The exhibition started in mid-August and goes until late October. If you go to the link above there are a number of images as well as audio clips of the specific chants found on the illuminated pages, thus quite nicely tying together the visual beauty of the books, their audible beauty, and ultimately their liturgical purpose. It sounds as though this is audio-visual aspect is likewise incorporated into the actual exhibition, where it has been noted that some who have come to the exhibition try their hands at the chants.
Today's Los Angeles Times also has an article on this exhibition.
The exhibition site also drew to my attention a rather intriguing Missal, the Stammheim Missal which has some very interesting illuminations whose style has a certain stylistic clarity about it which appeals to me: