Haven’t heard anything about this elsewhere:

Oceana, a 2.5-year-old nonprofit group, said Google dropped the text-based ads displayed in shaded boxes along the right side of its Web page because they were critical of Royal Caribbean Cruise Lines. Oceana believes Royal Caribbean pollutes the oceans by improperly treating the sewage on its ships, and hoped to publicize its complaints by paying to have its ads appear when terms like “cruise vacation” and “cruise ship” were entered into Google’s search engine.

Google’s policy prohibits ads criticizing other groups or companies, said a Google representative.