Here's the full press release from ECM Records:

Over the past week we have begun the process of entering streaming, and from November 17th, the full ECM catalogue will be available to subscribers to services including Apple Music, Amazon, Spotify, Deezer, Tidal and Qobuz. This simultaneous launch across the platforms – facilitated by a new digital distribution agreement with Universal Music – invites listeners to explore the wide range of music recorded by our artists in the course of nearly five decades of independent production.

Although ECM’s preferred mediums remain the CD and LP, the first priority is that the music should be heard. The physical catalogue and the original authorship are the crucial references for us: the complete ECM album with its artistic signature, best possible sound quality, sequence and dramaturgy intact, telling its story from beginning to end.

In recent years, ECM and the musicians have had to face unauthorized streaming of recordings via video web-sharing sites, plus piracy, bootlegs, and a proliferation of illegal download sites. It was important to make the catalogue accessible within a framework where copyrights are respected.

ECM Press Office
Munich, November 14, 2017

Most (all?) of Keith Jarrett's albums seem to be available.

Thanks to Luis and David for letting me know about this.