He just addressed it on the HuffPo. Key passages:
Let me say at the outset that I vehemently disagree and strongly condemn the statements that have been the subject of this controversy. I categorically denounce any statement that disparages our great country or serves to divide us from our allies. I also believe that words that degrade individuals have no place in our public dialogue, whether it's on the campaign stump or in the pulpit. In sum, I reject outright the statements by Rev. Wright that are at issue. ...
Most importantly, Rev. Wright preached the gospel of Jesus, a gospel on which I base my life. In other words, he has never been my political advisor; he's been my pastor. And the sermons I heard him preach always related to our obligation to love God and one another, to work on behalf of the poor, and to seek justice at every turn.
The statements that Rev. Wright made that are the cause of this controversy were not statements I personally heard him preach while I sat in the pews of Trinity or heard him utter in private conversation. When these statements first came to my attention, it was at the beginning of my presidential campaign. I made it clear at the time that I strongly condemned his comments. But because Rev. Wright was on the verge of retirement, and because of my strong links to the Trinity faith community, where I married my wife and where my daughters were baptized, I did not think it appropriate to leave the church.
This seems like as strong a statement as he can put out at this point. It doesn't implausibly distance him from a man that he's been tied to for 20 years (e.g., "I haven't had more than two or three five-minute conversations with him in my life") but does invoke a distinction a lot of church-going Americans can relate to, which is the distinction between a religious leader's religious views and his political views.
Whether or not this explanation does the trick depends on two things, I guess: 1.) Most obviously, whether Obama has really never heard Wright preach this kind of stuff. If Obama is somehow placed at a sermon in which Wright went on one of his rants, it's going to be a disaster. (Then again, it would have been a disaster without or without his HuffPo statement.) 2.) How plausible it is that Obama wouldn't have known about Wright's, er, greatest hits. Obama strongly implies he didn't know his pastor had a habit of giving nutty sermons up until the outset of his presidential campaign. Is that believable? Is there any way to disprove it? If the answers are "yes" and "no" respectively, then he'll weather this. If not, it could get uncomfortable.
Update [7:10 PM]: The more I think about it, the more I think Obama needs to go further. Part of the problem is we'll never be able to answer that first question strongly in the affirmative. Even if true, a lot of people are going to wonder how Obama could have missed this stuff during all his years of going to church.
More importantly, there's just too large an asymmetry between Obama's cool-headed explanation and the visceral power of those Wright videos. Fairly or not, it's the visual of Wright that will linger. I think Obama needs a more striking gesture of his own. Like announcing that he's removing Wright from his (largely honorary) position in the campaign, maybe giving a high-profile speech about his faith.
Update [8:10]: Wright has been dismissed from the campaign's spiritual advisory board.