Hey look! Disappearing bodies! No, this isn't some homage mod to the days of 8-bit fatalities, it's one of the features put into the Australian Left 4 Dead 2 so it could be approved for sale.
You can see for yourself in that video above. The scorecard, according to the Steam community forums is comprehensive: the Australian version of Left 4 Dead 2 will have no bloodspatter on the screen; there will be no zombie dismemberment; there will be nothing beyond a "small splash of blood" when you attack an infected - no guts or gore; infected won't light on fire if they get hit with a molotov, and corpses will disappear from the screen.
But wait, there's less! The bullet-proof Riot Cop uncommon infected will not spawn, I guess over cop-killing concerns? "If someone with an uncut version joins a game with Australians with the cut version, Uncommon Infected will NOT spawn," says the forums.
Wow. I was thinking melee would be subject to the two-hand touch rule. Good thing they saved that!
Kotaku Australia wrote up the full scoop - with a workaround to defeat the censorship. Although they point out this was tested only on the demo and may not work with the full release.
What's Cut From Aussie Left 4 Dead 2, And How To Uncut It [Kotaku Australia]