Ellen's voice in the trailer was made to sound like GlaDOS, it will sound slightly different in the actual movie.
http://kotaku.com/5973435/glados-did-appear-in-pacific-rims-trailer-but-wont-return-for-the-movie
http://kotaku.com/5973435/glados-did-appear-in-pacific-rims-trailer-but-wont-return-for-the-movie