BEGIN:VCALENDAR BEGIN:VEVENT DTSTART;TZID=America/New_York:20130726T090000 RRULE:FREQ=YEARLY;BYMONTH=7;BYDAY=-1FR DESCRIPTION:http://www.sysadminday.com/ LOCATION:Company wide SUMMARY:Sysadmin Day! BEGIN:VALARM ACTION:DISPLAY DESCRIPTION:REMINDER TRIGGER;RELATED=START:-PT15M END:VALARM END:VEVENT END:VCALENDARLive.com (The MSN then Hotmail and now Live, will Microsoft stop changing names at some point?) does support importing the above and it correctly allocates the slots however do not dare to try editing it because the edition interface does not support such statement really. Exchange OWA and Outlook will recognize the iCalendar and correctly allocate the slots but you won't be able to edit the occurrence after that.
Guess who got it right? Yup, MAC OSX did ;-) and as usual with an impressive can't-get-any-simpler User Interface. User experience is on the top of the list for Apple and that is why they can sell the most expensive equipment, they simply get it right. Steve Jobs was so correct when he stated "Design is not just what it looks like and feels like. Design is how it works."
And not only it works from the GUI but you can also import the iCalendar as well.