On Last.fm, I recently discovered some subtle form of market push. One of my favourite singers, Sissel, released a new album Northern Lights in November, and this album is actively pushed by last.fm: Occasionally when playing music of artists similar to Sissel, I will get a piece of Sissel herself playing as the first track. Despite the 5 or more albums available from Sissel on Last.fm, this track is always(!) a track of the new album.
You can try it for yourself: Start the last.fm standalone player and enter “Sissel” as an artist. Start playing the music. Watch if the first track played is from Sissel. If so, is it from “Northern Lights”? I bet so. (Stop and repeat if the track is not from Sissel)