The media generally did not attempt to nuance and distinguish between a sermon from a black pastor and a political statement from a politician. Instead, Obama endured continued guilt by association references to Rev. Wright and his ostensibly anti-American sermons. George Stephanopolis and Charles Gibson continued this political smearing in their infamous Philadelphia debate which also included Obama's relationship with Bill Ayers, a former member of a militant black group in 1968.
It is my personal opinion that the retired Rev Wright had seen this going on for 6 weeks while he had remained silent hoping that the issue would go away. Unfortunately it did not and was going to remain an issue for Obama all the way to November. Given that Rev. Wright is a capable, intelligent, and wise person I am sure that he knew the consequences of him going public about his previous sermons.
I think that Rev. Wright's going public with his defense of the black church and his previous sermons was meant to give cover to Obama to reject the good pastor once and for all. I am not suggesting that Obama planned this. I am convinced that Obama was just as surprised as many of his supporters about Rev. Wright defending his so-called radical views about America. However, giving Obama the opportunity to reject Rev. Wright as well as his remarks should put this issue away for the rest of the campaign.