Douglas Adams and Steve Meretzky went on to write a second game called Bureaucracy, with the same format as the Hitchhiker's Text Adventure. Bureaucracy was credited to "Douglas Adams and The Staff of Infocom" since there were lots of Infocom people involved (Jeff O'Neill, Dave Lebling, Fred Morgan and others). It was said, even at the time of Bureaucracy's release, that Douglas Adams simply provided the anecdote upon which the entire game was based, but wasn't involved in the rest of the game's production (Andrew Williams: "He probably had to duck out for a bath…")
Bureaucracy is one of the games included in The Lost Treasures of Infocom II (not to be confused with the first volume with the Hitchhiker's Text Adventure on it), and The Infocom Comedy Collection. It now also appears on Activision's newest collection of old Infocom games, called Masterpieces of Infocom, just released [when this answer was written, some years ago] on their "Essential Collection" budget label. This collection is very inexpensive (around £10, maybe about $10), runs on PC or Mac, and includes 30 or so other old Infocom text adventure games.