The Register explains how the filter has actually been running since about mid-February. Not all ISPs are onboard, only two are using the now voluntary filter with several more intending to do so. Public interest group, Tech Liberty, is working to pierce the silence by the Department of Internal Affairs and to raise awareness about problems with the scheme.
Nate Anderson at Ars has more technical details of the filter’s implementation. He also expands on Tech Liberties concerns over the whole plan, beyond the lack of judicial or governmental oversight. The system in question is a bit too coarse grained and likely to inadvertently block harmless sites.
I’ve expressed my concern with filtering systems many times before, namely they are never even anywhere close to perfect. Many researchers and activists have proved that other means of dealing with harms are far more effective than net nannies of any variety.