Setting up your iPhone is easy. Tap into your Settings app » Mail » Add account » MS Exchange. Then (copied from the instructions page):

• In the Email field, enter your full Google Account email address. If you use an @googlemail.com address, you may see an “Unable to verify certificate” warning when you proceed to the next step.

• Leave the Domain field blank.

• Enter your full Google Account email address as the Username.

• Enter your Google Account password as the Password.

• Tap Next at the top of your screen. (Choose Accept if the Unable to Verify Certificate dialog appears.)

• A new Server field will appear. Enter m.google.com.

• Press Next at the top of your screen again.

Done.

Works pretty well too.

UPDATE: Thanks to google, you can’t get push notification anymore.