This is a very interesting article about censorship in Australia. As much as Australia has one of the greatest ratings systems in the world (And America's is just plain bonkers a lot of the time), one thing we have an incredibly high amount of religious/family groups who like to demand things get re-rated or banned altogether. While movies such as the one they mentioned I'm sure probably warrented being banned (kiddie porn isn't good, okay) movies such as Irreversable and those in that ilk should NOT. The R18+ rating is there for a reason, you morons. It's not like you're going along to see SpongeBob SquarePants - it's rated R18+ for a reason.
It's funny that, speaking of that movie, SpongeBob got complaints over it's G rating. That's crazy cause... wtf?
However, if you read the article, there is a typo. Lost In Translation wasn't rated MA15+, but was actually rated PG and the complain would've been that the rating for that was too low. A pair of tits ain't enough for an M rating though. Unlike in America where it automatically warrents an R rating, yet you can have so much suggestive sexual stuff yet get a PG-13 rating purely cause your movie is targetted at a teen market.