Sync your GMail calendar with Thunderbird (Lightning)

bfish.xaedalus.net has posted a how-to to sync your Google Calendar with the Thunderbird add-on Lightning. It's great that it does not only support read access but writing calendar entries too. SpanningSync is a similar solution for Macs (Google calendar synced with iCal) but unfortunately that solution is not free. Last but not least: The solution works great in Thunderbird 2.0 too.