Ah, Mark Miller on promises! I am building a system (Spritely Goblins) which is very inspired by another system largely designed by MarkM, the "E" programming language. I'm borrowing most of the way promises work in E in Goblins. For those that don't know, the idea of promises in Javascript largely got ported from E, though not entirely (there are some things nicer about E's promises than Javascript's... promise pipelining is one clear one, and the "when" clause is much nicer than Javascript's .then() sausage-chains).
However I didn't realize that MarkM's work with promises predated E, that it started in his work on Xanadu... that makes sense.