As I argued here, the US right’s campaign against “political correctness” was something of a fraud. But the general point that, in any given political context, certain ideas are unthinkable and certain words are unspeakable is surely true.
Some times are worse than others in this respect, and I think Ross Gittins is correct to say that the pressure of political correctness is growing in Australia.

It seems to me that, in these days of unending chatter about current affairs, there’s a growing list of things you’re not allowed to say. For instance, you’re not allowed to say that, for the leader of the free world, George Bush doesn’t seem very bright.
You’re not allowed to say that John Howard won the last election by playing on the public’s fear of foreigners. You can’t say that, if life in the bush is so terrible, there’s no law stopping people moving to the city.
You can’t say that splitting up Telstra would be a good thing. And you can’t say that most company takeovers end up being bad for business.
But, above all, you can’t say that Australians aren’t overtaxed.

Gittins makes the point, well-known to everyone who has studied the subject that, because of the interaction of taxes and means-tested transfer payments, the highest effective marginal tax rates are those faced by low-wage families.