It is still very much a state by state matter. NSW has recent legislation on this, basically you need to have a legitimate purpose for having one if you are found in a public place with it. In Queensland there are no current extra rules, however common sense still comes into play. Victoria requires a license for owning/use, which will cost you more than most lasers. Other states/territories I am not currently up on, however I do know that many have exclusions available for legitimate recognised uses such as Astronomy.
Regards,
Eric