This really brings up the question "Where is the line between censorship and protection?" Also, here's the link to all the words you can't say.
Except that only blacklisted words for Google Instant results, not Google itself, which I don't think is a problem. Nothing worse than having porn instantly pop up when you mistype your search (Even if people don't mistype something similar to anal too much). If Google started censoring its results after you press enter thats when it might be a problem. I say might because when your looking for porn you most likely know where to look, and a you don't need Google to find it.
An interesting article but I think there would have been better examples to draw on. For the Google example, I also think that the service would be worse if they allowed the blacklisted words to auto-populate. I would not like to be the one making judgements about what is and is not acceptable for any of those companies, let alone developing the algorithms that help automatically 'filter' content.