Tom at SeeingRedInChina has a good post looking at why the censorship machine is letting so much noise get through on the Bo Xilai affair:
A second possibility, is that those in control of the Party (and no one is actually certain that there is a power struggle), want to make sure that Bo Xilai and his allies have been thrown completely under the bus. A number of stories have appeared about Bo’s Chongqing policies being reversed that support this theory. I also suspect this because my co-workers have been uncharacteristically well informed about the rumors, even though they don’t spend much time on Weibo, and don’t know how to escape the limits of the Chinese web. While there haven’t been any explicit descriptions of what has happened, there have been more nods than in the past.
I think this is probably pretty close to the mark, given how many fronts opened up so quickly in the attack on Bo. Some kind of anti-Bo coalition is definitely trying to inflict maximum damage on his political base, patronage lines, and ideology while he’s down.