Read the USCCB post on the Motu Proprio.
I would also refer the reader to extensive discussion of the MP hosted by the following bloggers.
The New Liturgical Movement
Some suggestions for celebratory activities from Fr. Erik Richsteig...
Let their be much rejoicing as the classical Roman Rite is freed! I had several thing planned, even before Carolina Kat suggested one in her comment on the previous blog. Perhaps a felt banner burn and barbecue. Perhaps skeet shooting with Glory and Praise pamphlets. Perhaps a rock throw using porcelain and glass vessels as targets. Best of all, driving slow around the local 'progressive' parishes blasting Palestrina and Plain Chant on the stereo with the windows rolled down.Read the rest here.
From the Society of St. Pius X (SSPX)
By the Motu Proprio Summorum Pontificum, Pope Benedict XVI has reinstated the Tridentine Mass in its rights, and clearly affirmed that the Roman Missal promulgated by Saint Pius V had never been abrogated. The Priestly Society of Saint Pius X rejoices to see the Church thus regain her liturgical Tradition, and give the possibility of a free access to the treasure of the Traditional Mass for the glory of God, the good of the Church and the salvation of souls, to the priests and faithful who had so far been deprived of it. The Priestly Society of Saint Pius X extends its deep gratitude to the Sovereign Pontiff for this great spiritual benefit.
The letter which accompanies the Motu Proprio does not hide however the difficulties that still remain. The Society of Saint Pius X wishes that the favorable climate established by the new dispositions of the Holy See will make it possible – after the decree of excommunication which still affects its bishops has been withdrawn – to consider more serenely the disputed doctrinal issues.
Lex orandi, lex credendi, the law of the liturgy is that of the faith. In the fidelity to the spirit of our founder, Archbishop Marcel Lefebvre, the attachment of the Society of Saint Pius X to the traditional liturgy is inseparably united to the faith which has been professed "always, everywhere and by all."
Menzingen, July 7, 2007
Bishop Bernard Fellay
The highly respected Vaticanisti Sandro Magister over at Chiesa has some insightful comments...
This is how the Mass was celebrated before, during, and after Vatican Council II, until 1970. If the passage to the new rite has created divisions and ruptures among the faithful, the fault is partly that of the Church: a fault which the pope now means to remedyRead the rest here.
Catholic World News (CWN) has an interesting and rather detailed analysis of the MP along with some glimpses of possible future implications. A few short snips...
Summorum Pontificum states flatly that the old form of the Mass, the 1962 Missal, was never abrogated. Implicitly the Pope is recognizing that many faithful Catholics have suffered a grave injustice, since they were told that the old form of the liturgy was now forbidden...Read the rest here.
...With his new norms Pope Benedict recognizes that many bishops have not allowed the "wide and generous" access to the old form that his predecessor had encouraged. Citing St. Paul's words to the Corinthians (2 Cor 6), the Pope now exhorts all bishops: "Let us generously open our hearts and make room for everything that the faith itself allows."
But Pope Benedict goes beyond exhortation, and establishes the rights of the faithful in terms of canon law. Every priest has the right to use the "extraordinary form," and needs no further permission. Wherever a "stable group" of parishioners asks for the old Mass, their pastor should "willingly accept" their request, the Pope adds...
...To be fair one must acknowledge that although many bishops have shown themselves unfriendly toward tradition-minded Catholics-- despite the pleas of John Paul II in Ecclesia Dei-- some traditionalists have been every bit as unfriendly in their attitude toward their bishops. Some traditionalists pounce on any opportunity to criticize the new liturgy, and a few-- a minority, certainly, but a very outspoken and divisive minority-- question whether the Novus Ordo liturgy is valid. The response to Summorum Pontificum in traditionalist circles will be another key test. If the motu proprio is warmly welcomed, that positive response might encourage bishops toward a generous implementation; if traditionalists fall into a pattern of carping criticism, bishops will feel that their hostility is justified.
This from an anonymous though grateful wit over at YouTube...