When the social connector is enabled in Microsoft Outlook and you have an Exchange mailbox, the social connector will sync changes in the GAL to contacts. It requires the user add contacts from the GAL to the local contact folder. (Many users save contacts so they can sync with phones or to have the contacts available offline.)
Yes, every change made to the GAL should be updated to Outlook's contacts. However, it's not instant - in fact, it can take 4 days for the changes to process and sync down to contacts.
The default setting for syncing with the GAL is 4 days. This can be changed using a global policy that adds or edits the following key. Note that the value is in minutes. (While you could sync as frequently as every minute, that is a bit excessive and can result in high network traffic - we recommend using the default, but if you need more frequent syncs, set it for no less than 24 hours (1440 minutes).
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\Outlook\SocialConnector DWORD: ContactSyncInterval Values: Any integer between 1 and 10080 (number is in minutes)
You can also sync changes immediately for any contact. Simply open the contact and click the Update button.
If the administrator doesn't want Outlook's contacts updated with data from the GAL, they can disable the synchronization using group policy. (Users can disable or control sync within Outlook, from the Social Connector's Settings dialog.)
The registry key that controls this is
HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\Outlook\SocialConnector DWORD: DisableContactGALSync
1 = The OSC does not synchronize Active Directory information with contacts.
0 = Policy disabled. (default) The OSC synchronizes data in the GAL.
If you're disabling this feature because the GAL is hopelessly out-of-date, you should consider giving users the ability to update their own records. For a list of utilities that provide self-service updates, see Active Directory Management Tools - User Updates
Disable global address list synchronization for Outlook 2010 (MSDN)
How to manage the Outlook Social Connector by using Group Policy (MSKB)