I agree with TmS, music is a life long ability and education. It truly is a gift for your child's entire life. Not many 80 year olds play football or soccer, but they can sing and play instruments.
Get all of the CDs and background music recommended by others. Most importantly, SING. Sing to your baby; sing with your baby. Music is both a language itself and in language. If you can talk, you can sing. Sing folk songs, nursery rhymes, pop songs, hymns ... it doesn't matter. Please don't fall into the 'performers only' cultural trap. I am so frustrated with the trend that only perfect artists are allowed to be heard. This idea has been absorbed by our society so that music is no longer a community activity but a spectator sport.
If you want your child to have music, model it to them. Children don't want or expect us to be 'American Idol' or Yiruma. If you don't do it, they won't try.
Now I will climb off my soap box podium. Sorry, I get a little passionate about the subject. It comes with the territory I guess. I am the creator of KinderBach because I wanted all children to have music as part of their basic education.