Cosmos magazine in Australia is collecting messages submitted through that site until August 24. Then the messages will be transmitted to the Gliese 581d exoplanet, 20 light years away. This planet is a recently discovered planet within the habitable zone of its star, and thus possibly containing water in liquid form, thus capable of life.
Despite being a near-shot in the dark, it's still quite a fun idea. Submit a message before the time runs out!