"The biggest surprise for us all internally at Sony was there are so many people who passionately reacted to our announcement that there's no MP3 support or CD support on day one. The focus has been more on the game features. Some of the features we wanted but we couldn't get in on day one."
This comes courtesy of an audio interview with Giant Bomb during Sony's big press event in New York. He is, at present, discussing with Sony on "when we can put these features in."