The site, HelloFromEarth.net, is accepted SMS style messages (meaning 160 characters or less) which will eventually be sent into space, directed at Gliese 581d, "a planet outside our Solar System which may support life."
Expected delivery date is December 2029 give or take a few months, the website says. Let's be honest, as well: they're not really using text messaging technology to send the message. There's also no guarantee of a reply. They might just "block" our number, so to speak.
The NASA/CSIRO Canberra Deep Space Communication Complex at Tidbinbilla, near Canberra, Australia, will use their 70-meter main antenna, known as Deep Space Station 43 (DSS43) to transmit a binary-encoded message consisting of all the SMS submissions combined, to Gliese 581d on August 24th, 2009.
Australia's Science Minister Kim Carr entered the first message in the list, to launch the project. It says "Hello from Australia on the planet we call Earth. These messages express our people's dreams for the future. We want to share those dreams with you."