The opening words of the Constitution show that the Pope regards this as a historic moment for Western Christianity. The Holy Spirit has driven Anglicans to seek full communion with Rome "repeatedly and insistently", he says. So he clearly believes it is his God-given mission to make special arrangements for those who are bringing with them "the liturgical, spiritual and pastoral traditions of the Anglican Communion ... as a precious gift".

The broad outline we already know: the former Anglicans will be given quasi-dioceses called Ordinariates, presided over by Ordinaries who may be ex-Anglican married bishops. The surprise, as I noted earlier, is just how much status these Ordinaries will be granted: they will sit on Bishops' Conferences and may even use their episcopal insignia. "Married bishops in all but name", is how Ruth Gledhill describes them. That's overdoing it, I think, since the married ones will not be in bishops' orders. She also says that this is "everything that Catholic Anglicans hoped for and more". Fair enough: it's more than many Anglo-Catholics were expecting, though I see there's a ban on Catholic clergy who converted to Anglicanism joining the Ordinariate (and quite right, too, in my opinion).

In addition to a structure of parishes, the Ordinariate will be allowed "houses of formation" for seminarians, though these will be incorporated in wider seminary training. The door is not closed on "case by case" ordination of married lay men, though it will be very much the exception rather than the rule. But here's a surprise: according to Article 7 of the Norms, "When necessary, priests, with the permission of the Ordinary, may engage in a secular profession compatible with the exercise of priestly ministry".

In other words, Ordinariate priests may work as (for example) teachers, doctors or social workers, just as Anglican non-stipendiary ministers may. Whether permission would extend to the private sector I don't know, but this is a clever solution to the problem of some ex-Anglican priests who would urgently need to support their families after leaving their previous ministry. (The Catholic Church can't afford to pay for many new full-time priests, that's for sure.) Also, Anglican priests already in secular jobs would be eligible to become Ordinariate priests. (I'm wondering if I dare point out that the Rev George Pitcher could "come over" and be the Telegraph's first Catholic priest religion editor - but that's about as likely as me defecting to Canterbury.)

Another notable feature of the Constitution: it makes provision for what are effectively new orders within the Ordinariate structure: "The Ordinary, with the approval of the Holy See, can erect new Institutes of Consecrated Life and Societies of Apostolic Life, with the right to call their members to Holy Orders, according to the norms of canon law." So the Pope clearly envisages the Ordinariate as a living and growing entity within the Catholic Church worldwide, not just England and Wales.

Ruth Gledhill thinks the problem of church buildings can and should be overcome (and it's nice to be able to praise one of her posts for a change):

This leaves the delicate problem of where these congregations will worship. Many are already talking of local ecumenical sharing agreements. In other words, congregations would divide into two - but still use the one church. Would the Church of England be generous about that? After all, the requests to The Episcopal Church for generosity in the case of its own departing flocks, and with all the local ecumenical projects embracing everything from Methodist to Orthodox up and down the land, it would look a tad hypocritical if dioceses began expelling priests and congregations whose only crime was to espouse the 'One Holy Catholic Apostolic Faith' in deed as well as Word.

However, don't expect any decisions about parishes, buildings or appointments for some time. The practical hurdles remain formidable - but my initial impression is that quite a few have been surmounted today.

----Damian Thompson is Blogs Editor of the Telegraph Media Group.