Google Apps for your domain and iPhone sync
Google has recently released calendar and address book sync for mobile and desktop devices using Microsoft Exchange protocol.
You need to follow a few simple steps on your iPhone to set it up. If you like me, use Google apps for your domain, you also need to enable mobile sync option. Go to ‘Manage this domain’ admin section, then ‘Service settings’ and ‘Mobile’. Under ‘Google Sync’ set ‘Enable Google sync’ check box.