John Hobbins has an interesting analysis of President Obama's use of scripture in his Tucson speech.
I agree with him that the use of Job is well-placed, at least on one interpretation of Job. The quotation comes from chapter 30, where Job is giving his final arguments after his "friends" have finished their attacks against him. It comes before Elihu's speech, were Elihu (rightly or wrongly) condemns much of what Job says in the preceding chapters, including chapter 30. On one interpretation, Job is righteous not just before his speeches in the book but in everything he says the entire book, and Elihu just repeats what the "friends" had said but without some of the uncharitable comments they make about Job's own words and without accusing him of particular things without evidence. On another interpretation, Job goes a bit overboard in his description of evil occurring from God's hand, and Elihu corrects him. If the former interpretation is correct, then President Obama has wisely picked a description of the evil that occurs in the world and its appearance to us without knowing the full context. If the latter interpretation is correct, then he's picked a bit from one of Job's over-the-top speeches that ignore the goodness of God in working through the bad things that occur in the world.
It's the Psalm 46 quote that gets John excited, though. He says Obama has masterfully taken the words of that psalm and applied them in a pre-critical, figural way that is very useful in civic religion. I wouldn't have put it that way. I'm not sure Obama has taken the words and applied them at all, in fact. He simply quotes a verse from the psalm and then moves on, leaving it to everyone hearing or reading his words to figure out what he might mean by it.
Read the text of his speech. He speaks of faith that Rep. Giffords will pull through and then quotes the psalm:
There is a river whose streams make glad the city of God,
the holy place where the Most High dwells.
God is within her, she will not fall;
God will help her at break of day.
He then goes on to speak of what happened in Tucson, as if the psalm quotation hadn't been there at all. I'm not remotely sure what President Obama even means to be saying by quoting this psalm in his speech. He doesn't explain it at all. He doesn't later apply it to this case. None of the language of the psalm appears anywhere else in the speech. He just reads a verse out of context and then changes the subject. It's like a bad sermon, where the preacher quotes a text and then just goes on to say whatever comes to mind, as if the text has nothing to do with the point of the sermon, there in order to make it sound remotely biblical.
His intent behind including this psalm can be taken in a number of ways, if we just go by the speech itself. He could be taking the reference of the City of God the way Augustine took it, implying that she is a Christian and therefore that the promises of the psalm can be applied to her. The river here, as intended in the psalm, would be God's means of taking care of his people. If so, and if she really is a Christian, I would have no problem with Christian application of the psalm in such a way. It would be taking the greater canonical themes and applying them in this psalm. But I have no reason to think Obama would restrict this psalm to Christians, given his pluralistic approach to religion.
He could be taking the city of God to be the United States, and the river would be God's means of taking care of the people of the United States. This is how I would most naturally take the use of this passage in a civic religion context. I'd be a little surprised if Obama thought there was some special relationship between God and the United States, though. But a lot of fans of civic religion would take it this way. This would be faithful to how the psalm is using this language within itself, but it would be getting the referent wrong (and there's no argument from later scripture for doing so, as there is in the Christian interpretation above).
One thing I would not conclude from his use of the psalm, however, is that he is identifying the river with Giffords, as John does in his post. It's so strongly at odds with what the psalm is doing that it would certainly not appear to me to be a charitable interpretation. I don't generally like to attribute such poor reading skills to an intelligent person like President Obama. I'm curious why John is taking him to be doing that. I know the first two interpretations are pretty unlikely unless he's just trying deliberately to be unclear and to have people take it in many different ways as they may be inclined (I'm not sure he's deliberately this way; he just is this way because of his relativistic proclivities, I would guess). But why is the river Giffords rather than Congress, the American people, Obama himself, or even Dick Cheney? There's nothing in the speech that gives a hint as to what he thinks the river is, what he thinks the city of God is, or what he thinks the holy place where God dwells is.
I have to conclude that Obama likes the metaphor but that he has given us no particular way of taking it, whether that's deliberate for relativistic reasons (something I wouldn't put past him) or simply because he has no idea that a metaphor needs to be given a referent in the context in some way (which would just be a sign of bad speech-writing skills). In neither case would I call it a "logical and audacious" transition. It's simply a bad transition, with no sense at all of what he's doing with it and no reason given for why it's even there.
It's no surprise to me that so many people had such high hopes for this president but were sorely disappointed once he had to start governing. He was the empty metaphor himself, standing for whatever the voters wanted to see in him, and when you include all the good anyone might want in a president, including several incompatible goals and hopes, there's no way to live up to it. He's doing the same thing here. I expect a number of other analyses from people who end up with completely different interpretation's from John's, all of them confident that they got him right and with no suggestion of any other ways of taking him. But perhaps that's, in a way, getting Obama right, if indeed his intent is to be so open-ended that people will take what they will (and I find that as likely as the alternative).