As we've noted before, Lightning makes Thunderbird soar above Outlook for home use, and places them on nearly equal ground in the office. The latest update includes an overhauled interface with easier-to-use buttons for jumping from your mail to your calendar, LDAP directory support for event invites, and Sun Java Calendar Server support.
Users of the daily build of Lightning will have been using many of the changes already, but for those who don't, the updates probably should be well received. A new menu bar for switching between mail and calendar views can live either above or below the folder tree. I find that when I place it above, making the jump between the two causes very little panel disruption.
On the right side of the main pane is a new panel for quickly viewing and managing events and tasks. It's option-heavy, so you can set it to show only events, only tasks, both, or hide the pane completely, as well as make changes to and create new events and tasks.
Events are now searchable through a search bar at the top of the calendar. Just below it is a hideable pane showing you upcoming events in a spreadsheet format. There are built-in presets for the next seven, 14, and 31 days, and they can be arranged by start date, end date, title, location, and calendar. Lightning supports multiple calendars, including iCals and has bidirectional support for Google Calendar with the Provider for Google Calendar plug-in.
There is also some support for Exchange servers. As it is now, if you receive an invite from somebody using an Exchange server, you can respond to and accept or decline the invitation. However, the next time you restart Thunderbird, the calendar will jump the time of the event.
I've worked around this by using the MR Tech Local Install plug-in's toolbar-based restart button to reload Thunderbird as soon as I accept an event, so that I can immediately go in and change the event time manually to what it should be. It's not perfect, but once saved, it retains the adjusted time.
Despite this hang-up, Lightning is an excellent plug-in for Thunderbird users, both lightweight and robust with features.