Eh, can't say I'm worried.
There was a big fuss made over some grand censorship program a few years ago, which wouldn't have worked. So the people behind it sat round looking foolish and feeling unhappy for a while. To cheer them up, they got Telstra, Optus and two others to pretend to have done something.
That's more or less it. Four companies voluntarily not giving access to a mere 500 sites, except if the user bothers to get round them to make it look like something is being done. No effect on people who use other ISPs, who'll be delighted by the new people signing up should it prove unpopular.
It's a pointless political stunt. The government can't take this much further because they're on shaky grounds as it is, one good nudge will see the opposition firmly in power next election. So they do something to appease the people who want something to be done, just not anything that'll change anything to appease the people who don't want change.
...
Also, the government can't simply track or otherwise deal with various child abuse sites, because they aren't in a jurisdiction with the same definition of child abuse as the Australian government, assuming the local laws are properly enforced. Hell, the federal and state definitions of "child" in Australia tend to vary, though Federal is the one that counts for the internet and postal system. In various states, you're free to look at 17 yr olds having sex, but not to send or receive them via post or internet.