Mozilla Sunbird is a free and open source, cross-platform calendar application that was developed by the Mozilla Foundation, Sun Microsystems and many volunteers. Mozilla Sunbird was described as "... a cross platform standalone calendar application based on Mozilla's XUL user interface language." Announced in July 2003, Sunbird is a standalone version of the Mozilla Calendar Project.
It was developed as a standalone version of the Lightning calendar and scheduling extension for Mozilla Thunderbird. Development of Sunbird was ended with release 1.0 beta 1 to focus on development of Mozilla Lightning.
Read more about Mozilla Sunbird: Sun Contributions, Trademark Issues and Iceowl, Release History