From TunesWiki

Syllable was born in July 2002 as a fork of the AtheOS operating system. Several AtheOS developers, concerned about the long-term development of AtheOS, created Syllable to ensure that development would continue.

The goal of Syllable is to create a reliable and easy-to-use open source operating system for the home and small office user. We also want to encourage developers to create an operating system that is intuitive, easy to use, and powerful.