Mac Os X 10.5.3, address book synchronizes with Google via iPhone
With the new 10.5.3 update for Mac Os X recently released, Apple would finally introduce the synchronization between the Address Book and Gmail contacts. To start the synchronization, simply tick the appropriate box in the general preferences, an option that appeared just below the box for synchronization with Yahoo !.
Once the option is selected, just enter the data of your Google account to start the synchronization between the two sections. Conditio sine qua non to take advantage of the functionality is to own an iPhone; that's right: unfortunately those who do not have an iPhone on will be able to take advantage of the newly introduced Apple / Google feature.
For those who have an iPhone in their hands, we recommend that you carefully read the related FAQ made available by Mountain View before completely twisting your address book.