From the BBC:

BBC NEWS | Programmes | Click | Spotify streams for music lovers
Music streaming service Spotify is only a few months old but it has already attracted much attention from music lovers.

The site allows its members to create and listen to heir own playlists of songs streamed to them online.

The same peer-to-peer technology as found in file-sharing is used to deliver near-CD quality and tracks that playback almost instantly.

The service is free for listeners willing to hear audio and on-screen adverts (which appear between roughly every five songs), although users can otherwise pay £10 per month for a premium service which enables them to listen to songs without adverts.

And from guitarist Robert Fripp:

Robert Fripp’s Diary for Thursday, 21st May 2009
The industry-word is that Spotify currently has little advertising to support it & few punters are signing up for the subscription service. In my view, Spotify provides an exemplary model of how the new, emerging music industry of digital provision works against the interests of music’s originators & generators.