OK, it's not the Motu Proprio that many (myself included) have hoped for, but Pope Benedict XVI has released his Post-Synodial Apostolic Exhortation, Sacramentum Caritatis (The Sacrament of Charity). Here are some excerpts:
1. The sacrament of charity (1), the Holy Eucharist is the gift that Jesus Christ makes of himself, thus revealing to us God's infinite love for every man and woman. This wondrous sacrament makes manifest that "greater" love which led him to "lay down his life for his friends" (Jn 15:13). Jesus did indeed love them "to the end" (Jn 13:1). In those words the Evangelist introduces Christ's act of immense humility: before dying for us on the Cross, he tied a towel around himself and washed the feet of his disciples. In the same way, Jesus continues, in the sacrament of the Eucharist, to love us "to the end," even to offering us his body and his blood. What amazement must the Apostles have felt in witnessing what the Lord did and said during that Supper! What wonder must the eucharistic mystery also awaken in our own hearts!
Respect for the liturgical books and the richness of signs
40. Emphasizing the importance of the ars celebrandi also leads to an appreciation of the value of the liturgical norms. (121) The ars celebrandi should foster a sense of the sacred and the use of outward signs which help to cultivate this sense, such as, for example, the harmony of the rite, the liturgical vestments, the furnishings and the sacred space. The eucharistic celebration is enhanced when priests and liturgical leaders are committed to making known the current liturgical texts and norms, making available the great riches found in the General Instruction of the Roman Missal and the Order of Readings for Mass. Perhaps we take it for granted that our ecclesial communities already know and appreciate these resources, but this is not always the case. These texts contain riches which have preserved and expressed the faith and experience of the People of God over its two-thousand-year history. Equally important for a correct ars celebrandi is an attentiveness to the various kinds of language that the liturgy employs: words and music, gestures and silence, movement, the liturgical colours of the vestments. By its very nature the liturgy operates on different levels of communication which enable it to engage the whole human person. The simplicity of its gestures and the sobriety of its orderly sequence of signs communicate and inspire more than any contrived and inappropriate additions. Attentiveness and fidelity to the specific structure of the rite express both a recognition of the nature of Eucharist as a gift and, on the part of the minister, a docile openness to receiving this ineffable gift.
Liturgical song (emphasis mine)
42. In the ars celebrandi, liturgical song has a pre-eminent place. (126) Saint Augustine rightly says in a famous sermon that "the new man sings a new song. Singing is an expression of joy and, if we consider the matter, an expression of love" (127). The People of God assembled for the liturgy sings the praises of God. In the course of her two-thousand-year history, the Church has created, and still creates, music and songs which represent a rich patrimony of faith and love. This heritage must not be lost. Certainly as far as the liturgy is concerned, we cannot say that one song is as good as another. Generic improvisation or the introduction of musical genres which fail to respect the meaning of the liturgy should be avoided. As an element of the liturgy, song should be well integrated into the overall celebration (128). Consequently everything – texts, music, execution – ought to correspond to the meaning of the mystery being celebrated, the structure of the rite and the liturgical seasons (129). Finally, while respecting various styles and different and highly praiseworthy traditions, I desire, in accordance with the request advanced by the Synod Fathers, that Gregorian chant be suitably esteemed and employed (130) as the chant proper to the Roman liturgy (131).
The Latin Language
62. None of the above observations should cast doubt upon the importance of such large-scale liturgies. I am thinking here particularly of celebrations at international gatherings, which nowadays are held with greater frequency. The most should be made of these occasions. In order to express more clearly the unity and universality of the Church, I wish to endorse the proposal made by the Synod of Bishops, in harmony with the directives of the Second Vatican Council, (182) that, with the exception of the readings, the homily and the prayer of the faithful, such liturgies could be celebrated in Latin. Similarly, the better-known prayers (183) of the Church's tradition should be recited in Latin and, if possible, selections of Gregorian chant should be sung. Speaking more generally, I ask that future priests, from their time in the seminary, receive the preparation needed to understand and to celebrate Mass in Latin, and also to use Latin texts and execute Gregorian chant; nor should we forget that the faithful can be taught to recite the more common prayers in Latin, and also to sing parts of the liturgy to Gregorian chant. (184)
Here's the whole thing, straight from the horse's mouth, and in plain English.
Hat tip: Domini Sumus