This was a solemn pontifical Mass that came at the conclusion of a Gregorian chant conference held at the Brigitinne Monastery "Our Lady of Consolation" in Amity, Oregon. The Mass was the crowning celebration of a 3-day conference on Gregorian Chant and the role of sacred music in the liturgy (see a news story here). You may view an album of wonderful photos of the event here, thanks to Marc Salvatore.
UPDATE: An unofficial transcript of the homily is available here.