http://www.google.com/support/forum/p/Google%20Mobile/thread?tid=1b27fcd343e0544a&hl=en (rephrased):
if you want to sync google contacts with iphone over the air using
google sync, you can… sync all contacts… this way you can leave
your already existing contacts on iphone and sync all google contacts
(remember that every email which contact you except spam is put into
all contacts… this means veeeery lot of contacts and some people
find this very frustrating)
Ok it basically claims that we can sync All Contacts (all people we have ever contacted) to our IPhone over the air.
But right now my IPhone is syncing only My Contacts group and is not syncing anything outside that group. How do I make it sync All Contacts ?
Best Answer
I don't know how to get the phone to sync with a different group than My Contacts, or to sync all the contacts, but as long as you aren't using My Contacts for filing now, then you can have every contact in two groups - "My Contacts" for syncing and your chosen group for filing and organization.
You can do this without destroying the rest of your sorting scheme by selecting all contacts in each group in Google Contacts, opening the Groups menu, clicking the checkbox next to My Contacts until it shows up as a solid check mark (not a slash), and then clicking "apply" in the same menu. By selecting the checkbox instead of the name and using Apply, you are telling the UI to add them to My Contacts without moving them; this is a standard bit of Google UI style.