Summorum Pontificum - official Latin text on the Vatican website.
Translation of Summorum Pontificum - on the Vatican website but labelled "unofficial."
The Holy Father's accompanying letter - English version on the Vatican website.
New Catholic at Rorate Caeli has produced a pdf of the text of Summorum Pontificum and the English translation in parallel columns.
Fr John Zuhlsdorf has some helpful and sensible introductory comments
Shawn Tribe at the New Liturgical Movement has a Brief Summary of the Pre and Post MP Scenarios which I think sums up a lot of important points - especially his summary:
Overall, the significant, general shift in the post-MP Church is of course the de-marginalization of the Roman liturgical tradition and a re-assertion of a hermeneutic of continuity.There are several other excellent posts on the New Liturgical Movement which offer informed and balanced commentary. Others have simply put a link to say something like "see informed commentary here" - a just recognition of the excellent quality of information and comment at that first class blog.
Fr John Boyle has a commentary with the insight and expertise of an experienced canon lawyer.
Fr Martin Fox has some good observations in his post Well, the pope done did it!. From the point of view of the "hermeneutic of continuity" I particularly like his summary:
This is about how the Church, and history, views Vatican II--and that's big This should signal it's time to stop using the "new v. old" Church and Mass way of explaining Vatican II. Sorry, that's both incorrect and now it's clearly unhelpful. The pope--the pope--is saying that's wrong. I know, a lot of us were told that, and on behalf of those who told you that, wearing a collar--I'm sorry. But the time has now arrived to stop.Sandro Magister: Benedict XVI Liberalizes the Ancient Rite of the Mass – And Explains WhyAs ever, he shows how to do religious journalism with accuracy and insight.
Phil Lawler give the Catholic World News analysis.
The Committee on the Liturgy of the US Conference of Catholic Bishops has obviously taken the opportunity given by the advance release of the document to the Bishops. In their Newsletter dated June-July 2007 just published, they have the English text of the Motu Proprio itself and the accompanying letter. They then have 20 questions on the letter itself, including a comparison of Summorum Pontificum with Quattuor Abhinc Annos and Ecclesia Dei Adflicta, and 10 questions on the ordinary and extraordinary forms of the Missale Romanum. There are one or two things to quibble with (the comparison of old and new rites especially) but it rather puts us to shame over here.