I have to wonder if Spotify has fallen victim to the siren's lure of "social". Perhaps they believe their future lies in integration with the social graph and news feed. If so (IMHO), they are sorely mistaken.
I believe some services already have you tweet or post that you've listened to a particular song. Zuckerberg seems to believe in "sharing and more sharing" [1] and automatic sharing. What would be the end result of this? On a particularly music-filled day I might send 100+ posts about songs I've listen to? Really? People will ever look at that?
If it's part of the main news feed, it's spam. If it's not, nobody cares... except Facebook, who can mine such data.
And maybe Spotify except... they already have access to this data (for their subscribers). It just makes no sense.
Spotify is also late to the party (in the US at least). Any kind of restriction like this is incredibly risky. Other established players don't have this restriction. While you can argue that "normal people" don't care, who recommends such services to family and friends? It's us.
And any player in the music space would be remiss to ignore the 800 pound gorilla in the room, being Apple's iTunes. iCloud launches soon. Honestly I think it'll kill a few of these "upstarts".
Also, I am less than convinced of the utility of mobile streaming. Bandwidth and connectivity are still issues. Increasing storage and all-you-can-eat subscription models seem like a far better solution (IMHO).
[1]: http://bits.blogs.nytimes.com/2011/09/23/zuckerbergs-unspoke...