Fallout 3 has been "Refused Classification" by the Australian Office of Film and Literature Classification (OFLC), according to a rumour posted by GamersHell.
Unlike New Zealand and almost every other country in the world, Australia lacks any rating above "M15+" for video games, so titles that might be rated R16 or R18 in NZ can end up being banned in Australia (or censored, like Grand Theft Auto IV).
Apparently the ban may be a result of the game containing use of the drug morphine as a stimulant. So expect it to be R16 or R18 in New Zealand. It has not been rated here yet. Fallout Tactics was the only previous release in the series that required a classification in New Zealand, and it received an R16 sticker.
The Australian ban is just a rumour, however if the game does contain drug use this would likely present a problem for classification there, so it is plausible. If true, the publisher, Bethesda Softworks, will have to decide whether to try for an appeal, or modify the game and resubmit it, or just not sell it to the Aussies.
Gameplanet is seeking confirmation from the New Zealand distributors of Fallout 3 as to what impact this could have on the local release, but at this stage there's no reason to think an Australian ban would affect its release here. It's due out early October.
We recently flew over to Sydney to see the game; be sure to check out our Fallout 3 Preview for more information.