Maybe there is something I'm missing to keep you from using it, but I've found the CalDAV support in iCal and iPhone 3.0 to do this very well.

No additional software needed, adding an item in any location updates the others within a few minutes, and after it is set up I don't need to think about it, it is pretty transparent.

Very occasionally I get errors in iCal that it couldn't find a calendar, but quitting and relaunching solves it, and to think of it I haven't really seen that since iPhone 3.0 came out. Perhaps Google tightened things up on their end to stave off issues.

I guess I am missing something too.

I have gcal sync to ical via caldav. But ical will NOT sync to the iphone over the air via mobileme.

So I assume you are just syncing via iTunes.

Using this workaround I have the primary gcal calendar syncing wirelessly to my iphone, instantly.

Now I would like to know how to do the same for all the additional calendars I have created via google.

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since 1984....