Google Contacts (http://www.google.com/contacts) is a very important part of Google Apps suite since its connected to Gmail.
Follow these simple steps to have all your contact synchronized between your LinkedIn, Facebook, iPhone, Outlook and Gmail / Google Contacts:
Step 1 – Outlook to Google synchronizationThis step is optional. Outlook can be synchronized using Google Sync tool available at tools.google.com/dlpage/gappssync.
Step 2 – iPhone to Google synchronizationThis step is most essential in the process. Use these instructions exactly to setup the interaction between iPhone and Google http://bit.ly/bklwL8.
Step 3 – Facebook to iPhone synchronizationThis step will add missing contacts from Facebook and update the profile photo of existing contacts (only of your Facebook friends).
Download the Facebook application from the AppStore on your iPhone and follow these instructions http://bit.ly/bS2dPo.
Step 4 – LinkedIn to iPhone synchronizationThis step will add missing contacts from LinkedIn together with their profile photo (if they have one in LinkedIn). This step is very important since most of the business contacts are on LinkedIn.
Download the LinkedIn application from the AppStore on your iPhone and then download all contacts to your iPhone address book. See http://bit.ly/d4sZXM for more info.
I recommend completely rebooting your iPhone before synchronizing the LinkedIn contact since the application uses a lot of memory and can crash if you have to many contacts to synchronize the first time.
Step 5 – Congratulations! All contact are now synchronized to Google Contacts.Visit Google Contacts (http://www.google.com/contacts) and see that all your contacts, including profile photos (for most of them are included). Use the Google Contact "Find Duplicates" button to merge any duplicates.
Keep using the LinkedIn and Facebook app on your iPhone in order to sync them to Google. If you update any contact on Google, they will automatically get updated on your iPhone as well.
Want more synchronization? Enable Contact sharingIf you are using Google Apps it easy to share contacts between all users in your domain and to achieve a global addressbook. Follow these instructions to enable contact sharing: http://www.google.com/support/a/bin/answer.py?hl=en&answer=47926
You can also add Google Apps contacts from your Dashboard. All contacts will then be available on URL: https://www.google.com/contacts/a/
Note! These steps are tested and worked 1st April 2010. Google offers Contact API (http://code.google.com/apis/contacts/) that will enable you to integrate and use all your contacts in other systems e.g. a CRM tool.
Another option is to export the contact from Google and use them with Excel or other application that supports importing of Comma Separated Value files (CSV).