The Sunbird Project – Standalone Calendar: Since they can’t use “Firebird,” Sunbird was the next best thing, I suppose.
The Sunbird Project is a redesign of the Mozilla Calendar component. Our goal is to produce a cross platform standalone calendar application based on Mozilla’s XUL user interface language. At the moment the “Sunbird” name is a project name. It is not official and may change in the future.
The screenshots look good.