Numerous times shows have been cut for television. It seems to happen more regularly with regard to British television than Irish television, anyway below are a number of clips that were removed when these shows were broadcast on this side of the pond.
Another political one, the IRA blowing up John Bull's Chip Shop in the Simpsons.
In another episode Mr. Burns is snapped by a papparrazo (spelling?) and says "Damn you, Papparrazo" or something to that effect. The Pappa word was edited out when it aired on UK tv after Princess Diana died.
AFAIK none of these parts were banned or anything, just edited out by the networks airing them. Anything similar happen in the US?
A number of times episodes of shows have been rescheduled, due to news events. IIRC after the Dunblane massacre an episode of Star Trek: Voyager was rescheduled.