iTunes: Syncing address book contacts with your Google contacts

Mac OS X

1. Install iTunes 7.7 or later.  The latest version of iTunes is available here.
2. Connect your iPhone or iPod touch.
3. Select your iPhone or iPod touch in the device list.
4. Click the the Info tab.
5. Select Sync Address Book contacts.
6. Select Sync Google Address Book contacts.
7. Click the Configure button.
8. Enter your Google Gmail ID and password, then click OK.
9. Sync your iPhone or iPod touch.

Microsoft Windows XP, Windows Vista, or Windows 7

1. Install iTunes 7.7 or later. The latest version of iTunes is available here.
2. Connect your iPhone or iPod touch.
3. Select your iPhone or iPod touch in the device list.
4. Click the Info tab.
5. Select Sync contacts with.
6. Select Google Contacts.
7. Enter your Google Gmail ID and password, then click OK.
8. Sync your iPhone or iPod touch.

Some things to be aware of when using this feature:

• Google uses email addresses as the unique identifier for each Gmail contact. If some of your contacts have the same email address, they may not all sync.
• Anyone you have corresponded with in your Gmail account will be included in this sync by default. You may want to review and edit the contact list in your Google Gmail account before synchronizing with iTunes.
• If you are using Mac OS X and need to merge duplicate contact information, consider using the merge contacts feature of the OS X Address book to further refine your contacts after syncing.
• If you are syncing your computer with MobileMe, remember that these contacts may sync to MobileMe as well. 
• This feature requires an iPhone / iPod touch, iTunes 7.7 or later installed on Mac OS X 10.5.3 or later, Windows XP Service Pack 2 or later, Windows Vista, or Windows 7. 
• Windows users must choose only one contact application to sync with -- Yahoo! Address Book, Windows Address Book, Google Contacts, or Microsoft Outlook.