http://www.facebook.com/siriusxm

You can follow a few of the channels on Facebook at the above address.
How Important Is Social Media To Sirius XM? VERY according to this article from Sirius Buzz.

http://siriusbuzz.com/how-important-...us-xm-very.php

I don't know how important it is to be on Facebook, but if you are on Facebook already, you may want to check out the satellite radio pages.