For those curious, the US government releases geocoded zip codes openly:
AFAIK In Canada and the UK a postcode gives you an exact address, or pretty close to (around 10-20 properties to each postcode?). In the USA and Australia, a post code just gives you a 'suburb' (hundreds to thousands of properties to each postcode).
I think it's largely based on how mail is distributed, as they are Canada Post identifiers. My 5000 person hometown has no delivery -- everyone goes to the one post office. But my apartment building has its own little postal box thing, which requires a key from the mailman, which is a special case compared to dropping in mailboxes on the rest of the street.
I don't suppose there's any postal workers on here to chime in?
The first line of the address (often just the house number) and the postcode are sufficient to yield the entire address.
> expressly forbidden to [...] use in any database and/or application for the purposes of providing, updating or maintaining any publicly available postcode look up or finder functionality;
You're not allowed to use the Australian post code database as provided by Australia Post to provide a lookup or finder functionality that's publicly available.
All of that data is approximated by the ABS from whatever body controls the "real" versions, but is 99% good enough for anything you'd want to do with it.
Australia Post, on the other hand, don't really use postcodes to deliver mail anyway, I've been told. They're a vestigal construct which are very prominent in people's minds but so fraught in the implementation that any systems which analyse them (including Australia Post's) work against them rather than with them. I didn't know about Canada's system — that sounds like a much better idea!
http://maps.google.com.au/?q=qld+4352
It's eight non-contiguous areas as far north as Caboolture and as far south as Casino, the biggest of which are not much larger than Brisbane City Council.
Edit:
There's a treasure trove in the post code boundaries of utterly bizarre things that only past houses being in weird places can at times explain.
http://maps.google.com.au/?q=act+2611 or this: http://maps.google.com.au/?q=sa+5710
They do charge a nominal fee, but the data quality is excellent and they have monthly updates.