The Lightning Project is a redesign of the Mozilla Calendar component. Its goal is to tightly integrate calendar functionality (scheduling, tasks, etc.) into Mozilla Thunderbird.
Some of our future goals are (none of this is implemented right now):
Better Thunderbird integration: email<->task linkage, Integration with the Thunderbird address book, iMIP support (meeting invitations)
Improved CalDAV support
Cached calendar support for offline calendar use
Device synchronizatio
The Minimo (Mini Mozilla) project has been focused on code-size and runtime footprint reduction, small screen usablity, and porting to small consumer devices.