
The Google Calendar team announced Monday the public release of its support for the CalDAV protocol. What this means is that you can now use Apple iCal with your Google Calendar, so you can work even when you're offline, sync almost instantly, respond to invitations from others and see the free/busy data of your friends and coworkers.
In addition, Google developers have whipped up a nifty
setup program for iCal that you should download as the first step towards
setting up Google Calendars to sync with iCal.
Google now also supports Calendar syncing with Mozilla Sunbird.