Below is an example of using iCalendar in RDFa. The ficticious event can have a reminder associated with it; when the user selects "Save to calendar" an iCal (.ics) or vCal (.vcs) file is created. This can then be saved and imported to Outlook, Google Calendar, and other calendaring applications; and the calendars of most mobile phones.
Please help me test it by adding the event to your calendar!
I'm doing something in five weeks' time at quarter to three. Hope to see you in Bristol for a couple of hours!