I recently bit the bullet and picked up an iPhone, and it’s been great… except that it can’t sync up with my Google Calendar. I had figured out a trick that allowed me to subscribe to a private RSS feed of my calendar in iCal, but that’s only a one-way deal.
I just came across some good news, though. Google has enabled CalDAV, which means you can easily have two-way syncing between your Google Calendar and iPhone.
Just follow these simple instructions from their support site, and your Google Calendar will appear in iCal’s list of calendars, and iCal will sync any changes to and from Google Calendar. If you’ve enabled syncing between iCal and your iPhone, you’re good to go.
There’s also instructions for getting this working with Mozilla’s Sunbird.
Update: Sorry to get your hopes up – this doesn’t work as expected because adding events on the iPhone are not synced back to your Google Calendar, just iCal. See the comments for details.