Hi everyone for those of you considering getting the soundtrack or already have it, I can now confirm that the soundtrack DLC was given an update a few moments ago (restarting steam will kick-start the update if you need it)
The new update to the Soundtrack DLC added the necessary additions so that the soundtrack can be played using Steams Music Player and will if you have purchased the DLC appear in your steam music player library.
In addition we have kept the zip file version of the soundtrack so that you can still copy that separately if you wish to.