The paper on it by Steele and Hillis is well-worth reading, as the language's fundamental mechanism of parallelism bears more than a passing resemblance to the MapReduce of 20 years later.
My impression was that MapReduce isn't so much parallelism itself, but rather a way of organising the execution of a programme to take advantage of parallel processors. (Maybe this is a meaningless distinction; I have never written (intentionally) parallel code, and am not familiar with the terminology.) In that sense, Apple's GCD (https://en.wikipedia.org/wiki/Grand_Central_Dispatch) is another well known possibility—one of, presumably, many.
http://diyhpl.us/~bryan/papers2/paperbot/25aa007a093cd69bbf0...
The paper on it by Steele and Hillis is well-worth reading, as the language's fundamental mechanism of parallelism bears more than a passing resemblance to the MapReduce of 20 years later.