Right now, many black hatters are planning attacks on the proposed internet filter and its accompanying blacklist. I recently (and anonymously) spoke to one such black hatter who said the plan was not to leak the blacklist (yet again), but to highjack it. Imagine the havoc one could wreak if one could start adding innocuous websites to the blacklist - even just temporarily.
The first website to be added, of course, would be Senator Conroy's site, followed by The Australian Christian Lobby's site, and those of other groups in favour of the filter. Imagine the embarrassment and the public relations nightmare that would cause Conroy's people.