In reply to planetmarshall:
> The complaint usually comes from the same people who complain about the "Politically Correct Brigade" because their joke about the gay Paki who runs the corner shop no longer gets laughs in the pub.
Or to put it another way...
http://tinyurl.com/h7p447t
The whole idea that "political correctness" is a threat to free speech is a somewhat slippery claim, and apart from possibly a very specific set of cases*, it's a load of bollocks. A threat to free speech is making saying certain things illegal, i.e. censorship/criminalisation. Our laws are pretty much spot on in this respect: there are loads of exceptions to the right to free speech, but as far as I'm aware, these are to do with stuff that's injurious to the rights of others (incitement, libel, etc).
What does happen frequently is that people who say stuff that is racist, homophobic, etc are made to feel marginalised (and they didn't used to get that treatment). They complain that their "free speech" is being "shut down", but they don't get arrested and what they say isn't censored. They just get told to shut up. This is not losing the right to free speech, it's a shift in social attitudes to norms where racism, homophobia, etc are considered unacceptable.
*I agree that the recent trend of universities banning speakers whose views the student organisers found distasteful is a step in the wrong direction, there should be open debate. Whether this is actually censorship and a threat to free speech is a different matter.