I second that, as do many others on AWS forums (https://forums.aws.amazon.com/thread.jspa?messageID=271852). Other comment in this discussion is that this new Sao Paulo region is more expensive than the rest of them - I guess it would be the same (probably even more expensive) for Australia. However I'm sure that many AWS customers would be more than happy to pay for it. Without it, CloudFront is not truly global.
It's pretty likely that AU will have more expensive pricing than most places. Amazon doesn't enter a market and ignore the cost base that applies to everyone in the market place.
EDIT: please fill out this AWS survey, apparently this could potentially speed up adding the Australian region: http://aws.qualtrics.com/SE/?SID=SV_9yvAN5PK8abJIFK