It is currently developed as a standalone version of the Lightning extension for Mozilla Thunderbird that provides a calendar to the mail management application.
The latest version is 0.8[5]. Version 0.3 of Sunbird, and its "sister project", Lightning, were scheduled to be released simultaneously in late September 2006[6], but a release candidate was not made until October.[7] Mozilla Sunbird is described as "...a cross platform standalone calendar application based on Mozilla's XUL user interface language."[8] Version 0.8 of Sunbird is also available in a portable version [9].
Version 0.5 was released June 27, 2007[10] and includes support for Google Calendar via an extension[11].
Sun contributions
Sun Microsystems has been contributing significantly to the Lightning extension project [12] to provide users with an alternative free and open source choice to Microsoft Office by combining OpenOffice.org and Thunderbird/Lightning. Sun's key focus areas in addition to general bug fixing are calendar views, team/collaboration features and support for the Sun Java System Calendar Server [13]. Since both projects share the same code base, any contribution to one of them is a direct contribution to the other.