The law was named after Melvin Conway, an early proto-hacker who wrote an assembler for the Burroughs 220 called SAVE. (The name `SAVE' didn't stand for anything; it was just that you lost fewer card decks and listings because they all had SAVE written on them.)
There is also Tom Cheatham's amendment of Conway's Law: "If a group of N persons implements a COBOL compiler, there will be N-1 passes. Someone in the group has to be the manager."