Thanks to Nick for noticing that the latest ECM Records catalogue lists "Concerts: Bregenz / München" as a 3-CD set:

"Keith Jarrett
Concerts
Bregenz /München
Keith Jarrett: piano
Recorded May and June 1981
ECM 1227–29 | 3_CD 279 4570"

Only the Bregenz concert was released on CD (in the 1980s?). "Part IV" from the Munich concert was later released on the "Selected Recordings" compilation in 2002. "Hymns/Spheres" was also re-released in January 2013, after years of being only available on vinyl (or as a single CD entitled “Spheres”), so it makes sense for "Concerts: Bregenz / München" to finally get a proper re-release on CD this year (hopefully, as the release date is not currently known).

Update (May 6, 2013). ECM Records confirms that "Concerts: Bregenz / München" will be re-released, but not "soon" (which could mean 2014 or later).