Released December 20th, 2013.
Important to note that in 3.5.5 and 3.5.6 there have been changes to the Music system sample rate which may affect your music. The default sample rate has been changed from 44.1KHz to 48KHz.
If you choose to stick with the 48KHz, you will need to update your Music assets to match that sample rate. If you don't wish to update the assets, you can revert back to 44.1KHz by using s_MusicSampleRate 44100.