Australian media classification groups are perfectly happy to allow ridiculous amounts of gore on screen. It's the interactivity with video games that pushes them over the edge [Eye roll].
In regards to the first L4D not being banned, it was because it wasn't as gory as the new one. It certainly WAS gory, but not enough to turn the censors heads in its direction. L4D2, unfortunately, has new lighting and melee weapons, plus the much touted locational damage effects Valve has mentioned, all of which add to high amounts of on-screen gore.
"But wait!" I hear you cry "What about Gears of War and Gears of War 2! Surely those games must have been banned for their gratuitous amounts of gore!". The answer is both happily and sadly, no. Happily because they're fun games. Sadly, because the only reason I can postulate that the media classification groups are hounding L4D2 is because of its "ties to reality". To clarify, the Gears games were very obviosuly set in an alernate reality/place/dimension, whatever you want to call it. L4D2 is set in the present day and contains themes of viral outbreak, mass contamination and common "poeple on the street" having to murder hundreds of others to survive.
Basically, gore is fine, so long as it can't be related to real life. That's the only justification which might make any sense to the ratings at the moment.
