I have a mac at work and a mac at home now. How to keep these in sync? Simple – Spanning Sync using Google Calendar as the shared central point. It’s not free, but it ‘just works’ (ok, Leopard had some iSync bugs in the early versions, but everything seems ok again now.) I really like how I can edit a calendar entry on my work machine and know it will eventually get synced to my iPhone when I sync that at home.
I actually talked about doing this kind of thing almost 5 years ago to the day – looking at that list of requirements its nice that it pretty much all works now. 2 things that are missing – I’d like my iPhone to sync automatically with my home iMac over bluetooth, and also it’s still too much effort to sync different calendaring systems (e.g. personal with Google Calendar, work with Exchange) together.
I actually like Google Calendar a lot, it’s fun that it implements those sharing features I talked about 5 years ago. I also think it has a better user interface than the iCal app on the Mac – I tend to find I enter brief details in iCal and then fill in the details on Google Calendar.
Update
Yes, I know .Mac is supposed to do all this too, but it was horribly broken when I tried to use it 3 months ago or so, and it doesn’t have something nearly as useful as Google Calendar as the web accessable / sharable part of the solution.