I guessed Justin Timberlake. I based it on the info she gave out. She said the childs age, where she lives which was where the movie was filmed, and the dads approx age and that the is a well known actor. He and Russell Brand were the only well known actors filming there at that time. Then she said he went back to LA so that kinda rules out Russell. JT was not yet married at the time but was in a relationship so he would have reason to not want anyone to know.