This is last call for http://tools.ietf.org/html/draft-daboo-icalendar-rscale . The draft was extensively discussed at CalConnect (http://calconnect.org/), previous IETF discussion is on calsify@xxxxxxxx .
The draft functionality is currently fully implemented in Google Calendar. You can try it out using proprietary Google Calendar API:
1. Follow this link: http://goo.gl/tKTUQZ
2. Click on Oauth2.0 trigger in the upper right corner to authenticate
3. Enter your Google Calendar e-mail into calendarId field
4. Click Execute, you should get 200 OK
5. Now your non-Gregorian recurring event is visible in UI, embedded calendar, and any client that doesn't do recurrence expansion by itself
Your comments are welcome,
Grisha