Like it says in the previous 1000+ posts about this in the forum, they are working on it and Spotify have announced that they are aiming for a release in Q1 this year. Somewhere between now and march 31, that is.
And it's Spotify who builds the app, not MS. (I do recall reading something about MS being involved, thou).
"Killing is wrong. And bad. There should be a new, stronger word for killing. Like *badwrong, or badong. Yes, killing is badong. From this moment, I will stand for the opposite of killing: gnodab."