If you have an iPod, Blackberry, or a few other select devices, you can actually control your player from the stereo head in the dashboard. I tried my friends iPod and it works really well, but unfortunately, I have an HTC Sprint EVO, which won't work. And although it will charge my EVO, the stereo head reports an "unrecognized device" error, and won't go away until I unplug the device.
You can, however, load up a USB jump drive with MP3's and play your music library that way. I haven't tried it, but according to the owners manual, it should work.
BTW - what's an OBS?
-Brad