This is more of a warning then anything else: notifysync will break your private events and make them public.
It seems that notifysync doesn't support the sensitivity tag in activesync. This wouldn't be a horrible by itself, except that it breaks the server side tag as well.
If you create a private event, it will happily sync to you BB, and if you watch the sync logs you will note a strange pattern. Every time the device syncs the server tries to push <POOMCAL:Sensitivity>2</POOMCAL:Sensitivity> and next sync the device pushes back with <POOMCAL:Sensitivity>0</POOMCAL:Sensitivity>. This is ok for a while, right up to the start time of the event, the server maintaining the private flag, but at the first sync after the start of the event the server seems to give up and the device wins, and the server now takes the public setting for the event.
Clearly thats a problem. We'll complain to notifysync but I wonder why zimbra gives up on stoping the change after the start of the event while it doesn't before.