A comment on this blog points this the new GIRM at the USCCB website. This is the document that makes the Latin text much clearer. It includes a firmer declaration concerning the centrality of Gregorian chant, a broadened permission to sing the Gradual instead of the Responsorial Psalm, and a much-constrained environment for the use of non-liturgical music and texts. In fact, a plain reading of this document would raise serious questions about most all music (and texts in music) that one hears in most any Catholic parish today.
Catholic musicians gathered to blog about liturgy and life