93%, few factors. Obama being the first African American candidate will drive up turnout in the African American community, and out of those who don't typically turn out that do very very few will be turning out to vote against Obama. Katrina may also play a bit of a factor as African Americans are even more disconnected to the GOP than they were prior to Katrina.
McCain is attempting to reach out with his recent commitment to attend that NAACP conference thingy, but there is almost assuredly a higher GOP->DEM conversion rate this election over 2004 than the opposite. I'm starting to think that this may be the strongest voting block in the last century for a national candidate.