Gmail one of the most Popular Email Service From Google, Recently Announced Push mail for i Phone ,i pod Touch and Windows Mobile service.Complete Google Sync (Email,Contacts,Calender) was already available for Android.Calender and Contacts sync Service available for i Phone, Windows Mobile and S 60 devices.
from Now you Can use Google Sync to get your Gmail  directly to your iPhone, iPod Touch And Windows Mobile device.

  You can set up only your Gmail, Without  contacts and calendar or choose all three ,as your wish.
For i phone Make sure Your i phone OS version 3.0 or Higher(for checking click Settings > General > About and scroll down until you see Version)if Software out of date check Apple's upgrade instructions.
Then Check m.google.com/sync for setting Instruction.

If you're already using Google Sync,just enable push mail.

After set up ,Your new mail normally pushed to your Mobile phone within seconds.

Trouble With setting?Just Visit


>>How to Set Up iPhone or iPod Touch for Push Email
>>How to Set Up ActiveSync on Windows Mobile for Push Email