First of all I open the dash and click the musical note icon. Then I search for an album or song. Now I've found it I want to send a link to my friend on facebook/twitter/google+. How do I do that?
Unfortunately, there isn't currently a way to do this. We used to have a feature in the plug-in for Rhythmbox, to share a link directly via Gwibber, but due to time and other constraints, we had to remove the feature while porting the plug-in to the new version of Rhythmbox, and all the related newer APIs.
Perhaps it is something we can bring back in Ubuntu 12.10 though. I do have a few ideas about how we could make it better than it used to be.