Courtesy of Fr. Scott Haynes (who will be an instructor at Missa in Cantu) here the music rubrics for high and low Mass, extraordinary form.
1. William Mahrt writes in the new issue of Sacred Music that Summorum Pontificum could inspire musical changes in all forms of the Roman Rite. The article is from the Fall 2007 issue of Sacred Music.
2. A 1907 book of liturgical choral music for 3 voices is now online, as edited by Ravanello.