Finally, there is a working and up-to-date tool to synchronize Microsoft Outlook contacts to Google contacts. The fork GOContactSync Mod is working smoothly and synchronizes all fields including categories and contact pictures.
Combined with Google Calendar Sync we’re getting close to replace Microsoft Exchange Server by Google Apps – only tasks are missing still. For Mac clients, Google Contacts synchronization is integrated in Mac’s own address book application anyhow – however, Apple missed out to synchronize the birthday field (which was added by Google later on). A simple possible workaround for that: on the Google Calendar web interface add a special interest calendar named “Your contact’s birthdays and anniversaries”. Then subscribe this calendar via iCal. The iPhone though will sync also birthdays from Google contacts.