I can confirm that the network binding engine in NT3 & NT4 contains a small prolog interpreter. Unusually blatant evidence for http://en.wikipedia.org/wiki/Greenspun's_tenth_rule .
I’ve talked to a couple of the guys who were charged with replacing the prolog interpreter in NT5. They wrote netcfg in a nascent programming language called C++, and were one of the first teams in the OS to use a new language feature called the “Standard Template Library”. Heady times, I’m sure.