Reopening this idea because it seems to have support and as the original poster stated, you did have this before so I don't see why it was removed or why if can't be added back in.
While recent versions of Spotify Desktop (e.g. 1.0.8) have got the "minimize to system tray" option again, this is simply just an icon which allows you to open the full Spotify window.
Obviously our attempts to get the minimize to tray option were not specific enough about wanting exactly the same functionality returned, so can we please have:
A system tray icon which has the same functionality (via right mouse click) as it did before it was removed, which was:
• Name of current track playing
• Open Spotify
• Option to Hide from task bar when closed
You had this before, so I dont see why you cant have it again.