Created at MIT, as part of Project Athena, Zephyr was designed as an instant messenger protocol and application-suite with a heavy Unix background. Using the "do one thing, do it well philosophy of Unix, it was made up of several separate programs working together to make a complete messenging system.
Zephyr is still in use today, mostly in University environments such as CMU, Stanford, and of course, MIT.
Related
- Gaim, a popular multi-platform Zephyr-capable client
