I don't have time to blog on this topic but there are few pieces I'd like to recommend.
First, of course, is my twin's piece at the Huffington Post where he looks at some of the influences that went into the speech. He argues that the speech used a variety of lines that taken in historical and literary context are less unambiguously positive than one might think. I'm tempted to argue that what Obama did amounts massive quote mining, taking many religious quotes simply out of context. Read the piece and be the judge.
There is also been some complaints in the atheist end of the blogosphere that Obama implied in the speech that all Americans believe in God. This strikes me as an opinion worth reading but overall is naive and misguided. Given what he did in this speech and what Obama is setting out to accomplish, I don't think people should seriously have expected any form of inclusion of atheists and agnostics that would not have resulted in backlash from the Islamic world. Obama explicitly mentioned non-believers in his inauguration speech. Be happy with that.
Also, David Horowitz has an interesting piece praising Obama's speech from a neo-conservative perspective. If David Horowitz is praising something Obama did, we can safely assume it was the correct thing to do.
Finally, see also Ed Brayton's piece also taking a very positive stance on the speech.