I wanted to sync my iPhone with my Google Calendar and Contacts, so I adventured myself with Google Sync. It’s not difficult to do it, just follow the instructions here very carefully.
After that, all went well but I wanted two other things working for full bliss: sync all my Google Calendars with my iPhone and my Mac’s iCal. Confused? Well, when I used Google Sync with my iPhone, it only synced my default Google Calendar, I had to access http://m.google.com/sync with my iPhone and specify which callendars I wanted to sync. Easy.
Syncing my Google Calendars with iCal was a little bit more trickyer, but found this article in Google help, that actually did all the work for me. This allows iCal to use CalDAV to access all your Google Calendars. You can configure the settings manually in iCal’s preferences or use Calaboration to automate it.
So, now I have all my Google Mail, Contacts and Calendar synced with my iPhone and Mac 🙂 All this for free. It’s getting hard for Apple to justify a paid MobileMe…
Hope this helps!