Canberra had a lot of enterprise focussed software startups which didn't get much notice; but I think compared to the US equivalents, alot of Australian companies fly under the radar.

My belief is if you're starting in the Aus rather than the US it doesn't really matter which city you're in as long as it's got a reasonable feeding uni. Having worked and recruited with US and Aus staff I definitely think Australian software engineers are some of the best and typically suitably pragmatic for software startups. (Until they fully roll out the US style of generalist and masters, aka uni melbourne approach, but I guess we'll see)