<http://www.thetaskforce.org/downloads/issues/egan_sherrill_prop8_1_6_09.pdf
>.
The relevant takeaway from the POV of the lbo-talk thread is that the black vote in favor wasn't statistically significant (in comparison to whites) after controlling for religiosity, but the significance re- emerges (significantly) if you additionally control for party and ideology. That is, religious blacks were no more likely to vote for Prop 8 than other religious people, but they were more likely to vote for it than religious white Dems/liberals.
Doug