Currently I'm unable to usefully import the existing user group iCalendar
file, because it contains recurring events with an initial meeting time
sometime last year. Here's how I propose we handle these:

* On import, create event instances based on the recurrence schedule,
ending either at the specified end date, or one year from import.
* Flag all recurring events with text like this:
http://skitch.com/spinnerin/mjc3/pdxfunc-monthly-meeting-calagator-portland-s-tech-calendar
* Treat all event instances that have been edited since import as
confirmed. This will encourage groups to add meeting agendas or other
details. Groups that have no new details to add could just add a
"Confirmed." line to the bottom of the description.
* Create a page that allows users to manage the 'master record' for
recurring events, extending or shortening their expiration, or changing
location and other details for following events.