When sharing calendars on iCloud, how do I show other people that I'm occupied, but not why?
The availability picker on Lion (when it even works) only shows the binary status with your busy times blocked.



The CalDAV request to show busy times just shows that you are busy, not why.

If you don't share private events (or keep that secure with a password to subscribe), your event details are as secure as anything on a web server with controls before you can retrieve the data. (not perfect security, but not wide open to anyone)