Apparently just before going off to bed, Joe Belfiore, corporate vice president and manager for Windows Phone Program Management has tweeted that a significant update for Spotify for Windows Phone 8 is on its way.
Spotify for Windows Phone 8 was released in February, and has not been updated since.
Now however an update will be coming which will add more language support, track scrubbing and offline playlist improvements.
The current version of the app can be found in the Windows Phone Store here.
Update: The updated app is now in store at the same link above.