Juan Williams op-ed in The New York Times is interesting. He claims that it is not impossible for Bush to get 20% of black support (he got 8% in 2000) because: 1) blacks have no enthusiasm for Kerry, and Kerry seems to be taking them for granted; 2) blacks as bloc voters is being questioned (for example, 34% of 18 to 25 year old blacks say they are independent, and 24% of all blacks say they are independent) and Bill Cosbys recent comments resonates with younger black voters; 3) black churches are generally supportive of Bushs faith-based initiative. Also, it is not irrelevant that there are many blacks in the highest positions in the administration. (Thanks to Ken Masugi)
Related to point #3 is the Bush Administrations strong stance against gay marriage which is supported to a large degree in the black Christian community.
I also think that the Democratic offer of affirmative action, welfare, and failed public schools is no longer resonating among young blacks or growing numbers of the black community.