The new Spotify client that just have been released have a couple of really nice features.
First, you can import all your local music files to it's library and play them from Spotify. (Wich means that I can uninstall winamp from my computer at work... )
Second, it has a facebook link so you can share and see what your friends listens to. If this is a good feature can be debated.
If the API is updated reflecting this change the MusicSpot can be made even more useful!