According to the Register, Google has killed the AdSense account of Enturbulation, a site ran by Anonymous, the group that's got their panties twisted in a knot over Scientology.
The reason is quite obvious: Enturbulation talks about Scientology a lot, and AdSense picks up the context wrong, serving a bunch of pro-Scientology ads there (which are, most probably, the only Scientology-related ads there are). Google's explanation for the cancellation, from their letter to Enturbulation, is this: "While going through our records recently, we found that your AdSense account has posed a significant risk to our AdWords advertisers. Since keeping your account in our publisher network may financially damage our advertisers in the future, we've decided to disable your account."