There are press stories floating around about a threat from Australia to file an application against Iran at the International Court of Justice for 'direct and public incitement to commit genocide', which is a punishable act under article III of the 1948 Genocide Convention. The Court would have jurisdiction under article IX of the Convention. The complaint concerns various speeches and other statements made by the Iranian president about Israel. Australia will have to prove that Iran had the intent to destroy the Jewish people, as such. This is not at all evident, given Iran's significant Jewish community which enjoys special political rights and freedom of religion.
The last word on 'direct and public incitement to commit genocide' is last November's ruling by the Appeals Chamber of the International Criminal Tribunal for Rwanda in the so-called 'media case', Prosecutor v. Nahimana et al.: http://188.8.131.52/default.htm.
It seems that Australia's new prime minister, Kevin Rudd, promised prior to the election that a Labour Party government would take action in the Court for Ahmadinejad's threats. Recently the Attorney General of Australia was quoted as saying: 'The Government considers the comments made by Iranian President Ahmadinejad, calling for the destruction of Israel and questioning the existence of the Holocaust, to be repugnant and offensive. The Government is currently taking advice on this matter. The alternative to not using these international legal mechanisms is considering wholesale invasion of countries, which itself involves, obviously, expense but more relevantly, of course, the potential for significant loss of life.'
My advice to Australia would be to let this idea die a natural death, as is often done with electoral promises made in the heat of the moment. Once the Australian lawyers have digested the Nahimana decision, they could consider the recent Bosnia v. Serbia ruling of the International Court of Justice in assessing their chances of success: http://www.icj-cij.org/docket/files/91/13685.pdf.