I believe he was referring to an unlimited sync-to-mobile, since he references unlimited storage in that sentence, as well. He's probably referring to a model like Rdio's.
I'm not a premium user but this page
http://www.spotify.com/us/get-spotify/premium/
implies that it's part of the package
"Add Spotify to your mobile phone and you’ll have immediate access to all that music - wherever you are, on or offline."
Yes it is part of the premium model. Offline playlists and mobile sync of those as well as other playlists is too. Sad to see them using the Facebook in such a short sighted fashion. They had till now been my best music service, not sure anymore.
