Google Apps Premier (GAP) is a service from Google that allows you to get all the benefits of Gmail with your own domain’s email. Great spam filter, the Gmail interface and now Google Sync for your iPhone or iPod. So if you have a GAP account and an iPhone you can now sync your GAP mail, contacts and calendar for free. Here’s how.
[step 1] Log into your GAP dashboard.
[step 2] Click on the Mobile link.
[step 3] Ensure that Google Mobile Sync is enabled.
That’s it. Now just follow the standard instructions for setting Google Sync up on your iPhone or iPod.