I'm trying to sort out a workable, scalable calendaring solution for the millions of things, people etc that I have to keep track of.  Google Calendar seems to be pretty nice, it has the ability to show and hide things, share calendars, delegate permissions etc.  I'm trialing it with some of the guys in Norway and hopefully will find a way to integrate Plone events (this website, the aboc.com.au site) with it somehow.  Adding things in multiple places is error prone and a PITA.  Watch this space ...