I haven't posted in some time, probably because not a lot has happened in the calendar world. There's been a new Calendar Interop by the Calendaring & Scheduling Consortium which included the first-ever interop for CalDav, a superset of WebDav which has some calendar folks excited. This Interop didn't include some of the previous participants, so I'm not sure how much progress is/was being made.
On another front, today there were suddenly rumors of Google Calendar (for one such post see Jeremy Zawadony's post), based on Google crawling for iCalendar (or Apple iCal, depending upon who you ask) data. This may be a manifestation not of a GCalendar application, but possibly of a specialized search for calendar information - which in and of itself would probably be a helpful thing. I suppose we'll know soon enough.