The original roar of Godzilla was made by a composer known as Akira Ifukube. The sound was produced by rubbing a leather glove that was resin covered along the strings of a double bass that were loosened and the play back was slowed down. The movie is set to be released either in 2012, 2013 or 2014 with no official reports on a specific date out yet. Read more details at http://en.wikipedia.org/wiki/Godzilla#American_films and http://en.wikipedia.org/wiki/Godzilla_roar.
The original godzilla roar came from the sound engineers recording the squeaking of the large hinged gate leading to the studio where godzilla was filmed. the sound was then slowed down to get the signature scream we hear today .