It's pretty fantastic: tapes have been found at the Library of Congress with recordings of a 1957 Carnegie Hall concert. Among the sets were eight performances, recorded by Voice of America (and apparently excellent quality), from Thelonius Monk and John Coltrane. And "the Dizzy Gillespie Orchestra, Ray Charles with a backing sextet, the Zoot Sims Quartet with Chet Baker, and the Sonny Rollins Trio."
The New York Times article notes that Billie Holiday "appeared as well, though she is not on the Voice of America tapes."
But it is Monk with Coltrane that constitutes the real find. That band existed for only six months in 1957, mostly through long and celebrated runs at the East Village club the Five Spot. During this period, Coltrane fully collected himself as an improviser, challenged by Monk and the discipline of his unusual harmonic sense. Thus began the 10-year sprint during which he changed jazz completely, before his death in 1967. The Monk quartet with Coltrane did record three numbers in a studio in 1957, but remarkably little material, and only with fairly low audience-tape fidelity, is known to exist from the Five Spot engagement.
The eight and a half Monk performances found at the Library of Congress, by contrast, are professionally recorded, strong and clear; you can hear the full dimensions of Shadow Wilson's drum kit and Ahmed Abdul-Malik's bass. It is certainly good enough for commercial release, though none has yet been negotiated.
For more on the tapes, how they were found and what else was found, read on...