Gmail is one of the most popular email and cloud services on the web. The iPhone natively supports Gmail syncing that includes email, contacts and calendars. While supported, the Gmail account will only be synced on a schedule, i.e. every 30min, 60min, or more. In order to enable Push functionality, such as a MobileMe account, you will need to add your Gmail address as a Microsoft Exchange account.
Before starting, make sure you have a valid Gmail account with your Username and Password. On your iPhone tap the Settings app. In the Settings menu, tap Mail, Contacts, Calendars.
The new screen will list the current email addresses associated with the iPhone. If you already have a Google account registered on the phone, tap the account and select Delete Account. When ready, select Add Account…
You will be presented with a list of email service providers. Tap Microsoft Exchange at the top of the list.
Enter your Gmail address in both the Email and Username fields. Leave the Domain field blank. Enter your password and type in a description for this account, such as My Google Account. Hit next.
After hitting Next, a Server field will appear. For this field, enter m.google.com and tap Next.
The option is now given to sync your Contacts, Calendar or Mail via Exchange. Slide the tab to the On position in order to begin pushing your content.
If you already have a MobileMe account, the Contacts and Calendars will be synced and placed into an additional folder in the Contacts and Calendar app. Setting up an Exchange Account on iPhone will actually drain the battery quicker than with the usual email account fetching. Any changes made on either the desktop, web or phone, they will be synced automatically.