For users of Google accounts, iOS provides a built-in way to access mail, calendars, and notes from Google. However, for users looking to get their email pushed to their device, or to synchronize their contacts, this built-in method doesn't work. But there is a way to do this, though, via Microsoft Exchange on iOS. This will allow for email to be pushed to the device, and for contacts to be synchronized to the iOS device. With iOS 5, it is also possible for notifications to appear in Notification Center, unlike in the official Gmail app, which only plays a notification sound.
This is a better method of contact synchronization with Google than doing it through iTunes. This means that contacts will be directly synchronized to and from Google when they are updated. This is great for those who have an Android device to go along with their iOS devices. This method also only synchronizes the main contacts; iTunes has been known to add all people that have ever been emailed. This method is safer and smarter.
Here's how to enable this feature on iOS.
Open up Settings. Tap on Mail, Contacts, and Calendars. Tap Add Account. Select Microsoft Exchange.
Enter the email address to be synchronized. The username is the same as the email address, and the password is the password to the account. The description can be anything the user wants. After submitting this information, a new Server option pops up. Enter m.google.com for this field.
If all the info has been successfully submitted, then the ability to enable/disable Mail, Contacts, and Calendar is available.
After all the information synchronizes, contacts from this Google account should appear in the Contacts app. Make sure that for new contacts to sync to the Google servers, set the Default Account in Mail, Accounts, and Calendars to the Exchange account. Multiple Exchange accounts can be synchronized, but only one account can have contacts added to it at a time.
Google does note that there are some drawbacks with Exchange sync versus standard account setup, but these drawbacks are well worth the trade-off for the enhanced feature set.