This litigation will, at minimum, be fascinating to watch. You might even want to make a donation towards the legal costs. In any event, go here to see what's happening.
Note for non-Australians: the High Court is, indeed, the highest court in the land. It's the equivalent of the US Supreme Court and has seven sitting members. The case is being initiated there rather than further down in the court system, as would probably happen in the US with an equivalent issue, because that's the only real way to challenge an action like the federal government's creation of the school chaplaincy scheme.