Fan site SimOperations has found the official Sims 3 soundtrack on EA Trax. You can listen to the 15 tracks online. With some tricks, you can get the playlist XML file, which shows the locations of the original MP3 files - which you can download and play on any other player which supports MP3 (hint: view the source of the playlist file, if you don't immediately see the URLs). The playlist also shows there should be 16 tracks, but number 9 seems to be missing. It may be revealed with the release of the Sims 3. The music was composed by Steve Jablonsky.