I was really beginning to wonder if we were going to ever see another Sunbird/Lightning release, but here it is, and it looks sharp. For those unaware, Sunbird is a standalone calender application that allows you to keep track of anything, make notes and plan for upcoming events. Lightning is essentially the same thing, except it’s integrated with Thunderbird, as an extension. The new version brings on a better looking GUI, improved printing and also support for Google Calendar (no surprise).
About two months after our initial scheduled release date, Lightning 0.5 and Sunbird 0.5 bring us a huge step closer to our 1.0 release, which is scheduled for the first half of 2008. Lightning 0.5 and Sunbird 0.5 are available for Windows, Mac OS X (universal builds) and Linux in 22 different languages including English.
Source: Calender Weblog