Valve has released the Steam Music Player today for anyone with a Steam client. The feature was in beta earlier this year, and has now been activated for the public.
Steam Music headlines
Steam Music beta invites have started rolling out, and Valve has also stressed that while it already sells game soundtracks on Steam, it may move into offering broader music and entertainment on the store in future.
Steam Music will be accepting beta testers soon, allowing you to leave off alt-tabbing out to fiddle with your volume balances in order to juggle music and gaming levels.