Simple AppleScript to set your iChat status to the current track in Spotify. The script checks every 10 seconds if there has been an update. If Spotify and/or iChat shuts down, the script will end. If you pause or stop Spotify, your iChat status will be set to Available. This also happens if Spotify is shut down but iChat is still running. I'm currently using Alfred to run the script, but you could save the script as a stand alone application or run it from the OS X script menu.