Syncing calendars... nothing is ever easy

I have a problem of managing multiple callendars. My wife has access to my Google calendar, my company has access to my Zimbra calendar. I use a Mac, and I like to use iCal if possible. I use Plaxo, TripIt and Dopplr, which provide ical interfaces/synchronisation, just like Google and Zimbra.

All this shouldn't be too original, so I expect that other people have this problem. Granted it is not an easy problem to solve, because synchronisation isn't easy. Let me first explain how I'm managing things now (and how I screw up). Then go over the options and then over what I really want.

Now I manage my calendars through CalDav. This works really well for a single calendar, but it does nothing for you in terms of synchronisation. If my office manager add's an appointment I see it show up in the right calendar, if I get a trip confirmation and send it to TripIt same story if my wife makes an appointment I can see it show up too. Nice overview, clear separation of calendars. Perfect, as long as I do the managing. That is the problem, my wife manages the calender of our private life, my manager manages the calender for the jobs. They have no idea what the other is doing.

So I screw up like this: if my manager plans for me to be abroad he checks with me and puts it in the calendar, then I have to make sure it shows in my private calendar that I'm abroad, otherwise my wife will plan something conflicting in the home calendar.

The underlying problem is that I am just one person, so everybody planning for me to be somewhere needs visibility on where I am. Main options:

• Be more disciplined and copy things over
• Use a single calendar and synchronize

The first option is what I'm doing now. Fine tuning this would mean I create a single calendar that lists my availability and make sure that all planners have read access to that from a single interface that they use for planning. The advantage is that this way the planners do not have to worry about fine grained appointments, just about available time (in a certain location).

The second option would allow me to be very lazy, but it would also result in a privacy issue where my manager can see that I went to a party on thursday evening or something. I don't care that much about privacy. I do care about my manager moving around my dentist appointment from the private calendar, so the solution is not ideal.

An ideal situation would allow me to share availability across calendars, and restrict write access and access to detailed information based on different calendars/sets of appointments.

The annoying thing is that there are no tools that allow this. Requirements are:

• Have to use Zimbra for work
• Have to use Gcal for private
• Want to use iCal as interface
• Want to integrate CalDav calendars
  
• No manual syncing

The only way to get close would be to install different sync utilities for my mac and sync with a local calendar. The proper way to do it is to allow CalDAV calendars to be synced in ical, but there is no support for this in iCal natively. The only workable solution (other than discipline) is to run sync utilities like Spanning Sync and the Zimbra iCal plugin. This is bound to screw up my calendars at some point I'm sure...