I foresee that Aussie L4D2 players will have to keep a low profile online. "You're an Aussie? Kick vote!" Assuming that is possible in L4D2 of course.

uh..
I think Aussies are just going to play on Aussie servers.

I would certainly recommend that. They won't be welcome anywhere else.

Neither will their ping.

Yet again, I apologise for letting my home state (SA) resident Mr Atkinson ruin everything by not giving us our R18 rating. It's not my fault of course, but I certainly did not vote for him in any way, and would like to see him removed with someone better asap.
I don't care much about L4D2, but its the lack of the rating itself that is the cause for strife.

also there are scripts that can ban by ip region (i.e. germany who also has the censored version)