According to the Australia and New Zealand Official Nintendo Magazine, Platinum has finally recieved a release date for Australia, being May 14th. The short section is as follows:
People like me will have to spend the next month and a halfThe Official Australia and New Zealand Nintendo Magazine said:
ATTENTION POKEFANS!
Get your wallets ready - Pokémon Platinum is primed for a 14 May release in Australia. It has already sold 2.4 million copies in Japan and comes packed with new features like fresh online modes and the ability to record your greatest victories on the Vs recorder. Expect the usual epic storyline and gameplay too, of course. Keep an eye on ONM for more soon...